can lightning travel in space

Lightning Across the Solar System

Lightning is as beautiful as it is powerful – a violent, hotter than the surface of the Sun electrical marvel. But might lightning on other planets be even more astonishing?

Consider this. When Voyager 1 flew by Jupiter in 1979, its imager captured areas nearly as big as the U.S. lit up by lightning in Jupiter’s clouds.

Voyager also captured other, less ‘flashy’ signs of lightning. University of Iowa physicist Don Gurnett is one of the scientists whose Voyager instrument detected radio waves called whistlers -- signs of lightning.

New Horizons cameras captured lightning flashes on Jupiter ten times as powerful as anything ever recorded on Earth. And recently Juno, flying closer to Jupiter than any previous mission, found that most of Jupiter’s lightning is around the planet’s higher latitudes, unlike Earth, where lightning strikes primarily over land and most intensely at the equator. Juno detected peak rates of four strikes per second -- similar to rates on Earth.

On Earth, lightning forms because colliding ice crystals and water drops inside clouds create positive and negative electric charges which become separated by convective forces. When the charges become separated enough, a lightning bolt discharges. Something similar happens on Jupiter. Gases, including water vapor, rise from deep within the planet. As they freeze, ice particles become separated from the water drops by convection, building a charge, which is discharged as lightning.

Lightning has also been observed on gas giant Saturn. In 1980-81, Voyager detected radio signals called sferics, which like whistlers are signs of lightning.

Gurnett says, “On Earth, you can hear these high-frequency radio emissions on your car’s AM radio as ‘radio static’ during a nearby lightning storm.”

Cassini recorded similar emissions at Saturn, revealing that, for strong storms, lightning occurred as many as ten times per second!

Gurnett has been involved in the search for lightning on other planets across the solar system as well.

Venus, for example, has a hot, dry atmosphere made up mostly of carbon dioxide suffused with sulfuric acid. Could this brew become electrically charged and generate lightning? When Cassini flew by Venus twice in 1998 and 1999 Gurnett did a search for lightning with a radio instrument perfect for detecting signs of lightning sferics. However the instrument picked up no signs at all. That same instrument easily detected sferics during a similar flyby of Earth two months later, leading him to believe that there is no Earth-like lightning present on Venus.

The European Space Agency’s Venus Express orbiter has picked up bursts of electromagnetic waves some scientists attribute to whistlers, but others argue that the instrument’s frequency range was too low to detect the usual forms of whistlers.

Gurnett has used Mars Express’s radar system receiver to conduct a five year search for lightning associated with dust storms on Mars. That search didn’t find lightning, however, images from the Mars Global Surveyor show bright flashes in dust storms, as well as craters on Mars that some scientists believe to be evidence of lightning strikes on the planet’s surface.

Stay tuned as this electric story unfolds on science.nasa.gov .

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• Published: 11 June 2021

Electromagnetic power of lightning superbolts from Earth to space

• J.-F. Ripoll   ORCID: orcid.org/0000-0002-1177-519X 1 , 2 ,
• T. Farges   ORCID: orcid.org/0000-0001-6496-144X 1 ,
• D. M. Malaspina 3 , 4 ,
• G. S. Cunningham 5 ,
• E. H. Lay 6 ,
• G. B. Hospodarsky 7 ,
• C. A. Kletzing   ORCID: orcid.org/0000-0002-4136-3348 7 ,
• J. R. Wygant 8 &
• S. Pédeboy 9  

Nature Communications volume  12 , Article number:  3553 ( 2021 ) Cite this article

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• Atmospheric dynamics
• Magnetospheric physics

Lightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. From burst-triggered measurements, we compute electric and magnetic power spectral density for very low frequency waves driven by superbolts, both on Earth and transmitted into space, demonstrating that superbolts transmit 10-1000 times more powerful very low frequency waves into space than typical strokes and revealing that their extreme nature is observed in space. We find several properties of superbolts that notably differ from most lightning flashes; a more symmetric first ground-wave peak due to a longer rise time, larger peak current, weaker decay of electromagnetic power density in space with distance, and a power mostly confined in the very low frequency range. Their signal is absent in space during day times and is received with a long-time delay on the Van Allen Probes. These results have implications for our understanding of lightning and superbolts, for ionosphere-magnetosphere wave transmission, wave propagation in space, and remote sensing of extreme events.

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Introduction.

Lightning superbolts are rare and extreme events that were first identified from optical stroke data measured by a photometer on board the Vela satellites 1 , 2 , yielding between 10 11 and 10 13  W per stroke. With such high radiated power, the temperature in the core channel of the stroke must exceed the commonly accepted maximum temperature of the lightning return stroke 3 , 4 (i.e., ~3 × 10 5  K) 5 , creating a debate concerning our current understanding of the energy balance in a lightning discharge 3 , 6 . Recently, radio frequency (RF) superbolts were geographically localized 7 using the tail of the occurrence distribution in lightning energy 8 , defined as above 1 MJ (1000 times greater than the 1 kJ mean), measured by the very low frequency (VLF) ground stations of the World-Wide Lightning Location Network (WWLLN) 9 , 10 , 11 , 12 . Interestingly, the distribution of superbolt locations and occurrence times was not equivalent to that of ordinary lightning: instead, superbolts were found to occur over oceans and seas at a much higher rate, and more often in winter 7 . The north Atlantic (west of Europe) and the Mediterranean Sea have some of the highest wintertime occurrence rates of superbolts 7 (see Fig.  1 and methods subsection Ground-based measurements of superbolts). As with any cloud-to-ground (CG) lightning flash, superbolts emit electromagnetic radiation in the very low frequency band that propagates within the Earth-ionosphere waveguide and escapes to the magnetosphere as whistler-mode waves along Earth’s magnetic field lines 13 .

All European (gray circles) WWLLN-detected superbolts in 2012–2018, among which we highlight the superbolts measured by Van Allen Probes (RBSP) in (black circles) survey and (pink circles) burst modes. WWLLN superbolts seen in coincidence by (blue circles) ECLAIR and (red circles) both ECLAIR and Météorage ground measurements. (large pink circles) Synchronized observations from both space and ground with WWLLN, Van Allen Probes burst and ECLAIR. The red dashed circle defines a 1500 km radius centered on the black triangle indicating the location of one of the ECLAIR stations used here. The x and y axes are longitude and latitude, respectively. The map itself is made with ©Matlab Mapping Toolbox.

Here, we show superbolt VLF electromagnetic (EM) power density in space. We combine space and ground-based measurements in a unique manner to follow electromagnetic superbolt signals from Earth to space over thousands of kilometers, to widely characterize their VLF electric and magnetic wave power density in space and on Earth, to compute ground-space transmitted power ratio, and to extract statistical electromagnetic properties of lightning superbolts never before reported. We conclude that, in addition to a location bias, superbolts exhibit other properties that differ from ordinary lightning, deepening the mystery associated with these extreme events.

Superbolt electromagnetic power

Superbolts are first located world-wide by making use of the WWLLN database, with an identification of superbolts from their energy greater than 1 MJ from synchronized measurements by WWLLN ground receivers 7 . In Europe, we make use of electric field measurements from a ground measurement campaign (ECLAIR) 14 , 15 conducted by CEA as well as data recorded by the stations of the French lightning location network, Météorage (MTRG) 16 (see methods subsection Ground-based measurements of superbolts). In space, we use two instruments 17 , 18 on board the NASA Van Allen Probes mission 19 to identify superbolt electric and magnetic wave fields (see methods subsection Space measurements of superbolts) from high-definition recordings. Superbolts signals are then gathered and retained after a selective screening process (see methods subsection Superbolt detection and selection). High-resolution electric power spectral density (PSD) from a selection of 6 superbolts is shown in Fig.  2 , from space (a1–d1) and ground-based (e1–f1) measurements. The black line in Fig.  2 (a2–f2) is the wave electric (magnetic) intensity, E 2 in V 2 /m 2 ( B 2 in pT 2 ), more commonly called, the wave power, which computation from the PSD is explained in the method section. In space, burst-mode spectrograms (Fig.  2 a1–d1) show superbolt VLF waves have a clear whistler-mode descending tone over a time period of seconds, as with all lightning-generated whistlers 20 , due to frequency-dependent dispersion through the ionosphere and plasmasphere. Their PSD frequency range spans ~0.1 to ~10 kHz, with most power above 2 kHz 21 and within the first second. The sharp rising tone just prior to the descending tone shape (e.g., Fig.  2 d1 for frequencies within ~10 2 and ~10 4  Hz at t  ~ 0.4) is an anti-aliasing filter that should be disregarded. Superbolts are observed in space with a time delay of 0.1 to 0.4 s from the superbolt WWLLN recorded time that marks t  = 0. The delay corresponds to the time the wave takes to propagate away from the stroke location, along the Earth-ionosphere waveguide, and then through the ionosphere into the magnetosphere along field lines and ultimately to the satellite. In some cases, the wave propagates to the magnetically conjugate footprint and reflects back before being seen at the spacecraft (see discussion below related to the superbolt of Fig.  3 ). Event times of all WWLLN events in the satellite burst window are marked with dashed vertical lines in Fig.  2 (bottom line plots, with the superbolt time indicated in red and non-superbolt lightning signals in green). An empirical estimate of the median squared electric field at the satellite location is calculated and reported for each of these strokes 22 , 23 based on both the estimated WWLLN total energy on the ground and the distance of the event (circles in the bottom line plots). The non-superbolt median squared electric field estimates (green circles) are lower than the superbolt estimates (red circle), by >3 orders of magnitude, confirming that the detected space-based signals only correspond to the WWLLN superbolt, and are not caused by other lightning.

a – f Show electric power spectral density and squared electric field (intensity) versus time for six different superbolts measured either ( a – d ) in burst mode in space (PSD in mV 2 /m 2 /Hz) or ( e , f ) on the ground (PSD in V 2 /m 2 /Hz). The specifics of the events are in Supplementary Tables  2 and 3 . Panel a1, b1, c1, d1, e1, f1 show the evolving power spectral density. Panel a2, b2, c2, d2, e2, f2 show the evolving wave electric field intensity. Panel a3, b3, c3, d3, e3, f3 show the average of the PSD over 1 s (in V 2 /m 2 /Hz). Dashed vertical lines in the line plots (a2–f2) show times of all WWLLN-detected lightning during that time interval. Circles in the line plots (a2–f2) indicate an estimate of the median squared electric field in space based on WWLLN-measured lightning energy (computed from ref. 22 ). The non-superbolt median squared electric field estimates (green circles) are found to be >3 orders of magnitude less than the superbolt estimates (green circle with a red contour), confirming that the detected space-based signals correspond to the WWLLN superbolt, and are not caused by other lightning. Continuous signal at ~20 kHz (e1–f1) is due to a powerful VLF ground transmitter and should be disregarded. The sharp rising tone just prior to the main whistler profile in (a1, c1, d1), best seen in (d1) at t  = 0.4 s for frequencies within 10 2 and 10 4  Hz, is an anti-aliasing filter effect with a fold over of the power above the top frequency.

(Left) Space and (right) ground simultaneous measurements of a superbolt (1.2 MJ) detected by WWLLN with t  = 0 at 2013/01/23-17.43.55.121 UTC. In space, we display the Van Allen Probes (RBSP) burst-mode measurements versus time of a the electric field power spectral density (PSD in V 2 /m 2 /Hz) measured by EFW, b the evolution of the squared electric field (intensity) and estimated time at the satellite of all WWLLN-detected lightning strokes in the time window (dashed vertical lines), and c the satellite-detected waveform with the survey acquisition and burst integration windows. (right) On the ground, we display (with same units) the evolution of d the electric field PSD in V 2 /m 2 /Hz and of e the squared electric field, f the electrical field waveform and g its zoom. The electric field PSD ( a ) has a characteristic descending tone shape in space (between t  ~ 0.4–0.6 s) but shows a second wave (starting at t  ~ 0.6 s) that is the bounce reflection of the primary wave. The sharp rising tone just prior to the descending tone shape (for frequencies within 2 × 10 2 and 9 × 10 3  Hz) is an anti-aliasing filter effect with a fold over of the power above the top frequency that should be disregarded. The estimated median squared electric field (in mV 2 /m 2 ) (following 22 ) of all other lightning is reported in b with green circles (#2–#10) and are found to be much lower than the superbolt’s intensity and its estimate (#1 green circle with a red contour) (more detail in Supplementary Table  4 ). The superbolt frequency decreases below 400 Hz (deep in the whistler-mode hiss wave band) after 2 s ( a ). See Supplementary Fig.  6 for more detail on space measurements and Supplementary Fig.  7 for more detail on ground-based measurements.

Simultaneous ground-based and space measurement of a superbolt

The closest of the two superbolts (1.2 MJ) that we observe synchronously from Earth and space is represented in Fig.  3 (more detail in Supplementary Fig.  6 and Supplementary Fig.  7 ). The waveforms (3c and 3f) are decomposed by Fourier transform to produce electric field (3a) and magnetic field (Supplementary Fig.  6e ) PSDs. Other lightning activity (Fig.  3c ) is composed of nine lightning events identified with WWLLN, listed in Supplementary Table  4 , and plotted on a map in Supplementary Fig.  7f . Among these nine normal lightning events, event #3 is a strong 95.8 kJ stroke occurring ~2 s later. This lightning activity is also visible in space with whistler-mode waves (3a), showing good temporal alignment with the WWLLN signal and representing significant wave power (line plot in 3b and WWLLN estimated power) for times between 2 and 3 s. Nevertheless, this activity does not mask or perturb the superbolt burst-mode signal which persists for ~1 s of the first ~1.4 s of data. The superbolt signal is found to be composed of one main wave (with a 0.4 s delay from WWLLN detection time) and a second similarly powerful wave 0.2 s later (3a, 3c). The time it takes for the wave to travel from the satellite to the magnetically conjugate point along the field line at L  ~ 2.43, reflect, and return at the equator is 0.2 s. Computing the Poynting flux (see Supplementary Method  1 ), we find a change of sign between these two waves, which indicates the second wave reaches the spacecraft from the opposite side of the field line. In the absence of any other event attested by WWLLN and since the time delay is consistent with one reflection, this suggests the two superbolt’s waves have entered the magnetosphere at different latitudes surrounding the source, followed then different paths, with one wave reaching first the spacecraft and the second reaching the spacecraft 0.2 s later after bouncing at the conjugate point of the field line. This is one of the plausible and classic scenarios obtained from ray-tracing simulations 24 . The peak squared electric field measured by an ECLAIR ground station for this event is 20 (V/m) 2 1387 km (3e) from the source. The average squared electric field over its duration (1.5 ms) is 4 (V/m) 2 , about 400 times greater than cloud-to-ground lightning measured on the ground (cf. discussion below). Quantifying the power spectral density on the ground is critical for validating ray-tracing simulations that predict the wave propagation from the source to space. The ground electric field peak (Fig.  3f and Supplementary Fig.  7e ) is well resolved (at 0.08 µs from the 12.5 MHz acquisition) and presents a longer-than-average rise time (the time for the signal to go from 50% to 90% of peak magnitude), which is confirmed to be specific to superbolts from rise time and fall time statistics below. This leads to a somewhat more symmetric first peak. In space, the northern magnetic footprint of the Van Allen Probes North (3c) is 3193 km away from the superbolt location and the measured peak squared electric field is 6 × 10 −7 (V/m) 2 , for a mean value of 8.5 × 10 −8 (V/m) 2 over 1 s, about 200 times higher than for normal lightning 21 . The root mean-squared (rms) amplitude of the magnetic field (3c), essential to compute pitch angle scattering of radiation belt electrons caused by lightning-generated whistlers in space (see review ref. 25 ), is 19 pT, 19 times larger than for normal lightning 21 . However, this is not as large as some of the superbolts we discuss next.

Propagation and attenuation of superbolt electromagnetic signal

The method displayed in Fig.  3 (Supplementary Figs.  6 and 7 ) was applied to each of the 66 superbolts observed in burst mode in 2012–2018 (cf. list and characteristics in Supplementary Tables  5 and 6 ), to analyze electric and magnetic field magnitudes in space. Ground squared electric field and PSD is similarly extracted from the 368 ECLAIR ground measurements of superbolts 26 . Mean-squared electric and magnetic fields are computed over a time period starting at the WWLLN superbolt time and lasting 1.5 ms on the ground and 1 s in space. These means are then plotted in Fig.  4 , scaled by the WWLLN energy, and plotted against distance from the source in order to present a unique global view of superbolts’ electromagnetic mean power density on Earth (Fig.  4a ) and in Space (Fig.  4b, c ). We find that ground EM power decay follows an inverse power law with a power ~2 over distance, which confirms a well-known far-field decay for EM waves in free space. In space, at the equator, superbolt EM power decays with an inverse power law with a power ~1.6 over distance. In comparison, normal lightning VLF power decays with a power law varying between ~1.7 27 and ~2.3 23 when measured from space at low altitude (~700 km) (see also ref. 28 ). VLF power loss between ground and space is expected due to wave power spreading out globally in the Earth-ionosphere waveguide and attenuation of the VLF signal by the atmosphere/ionosphere during propagation. The variability of power in space among individual superbolts with similar energy and distance is also found to be large (1–2 orders of magnitude). This variability is consistent with the great variability in L-shell, longitude, local time, and season of all lightning-generated waves 21 . However, such a variability limits the utility of the power density laws of Fig.  4 and put forward the need of reliable full modeling 29 .

a Mean-squared electric field from 2 to 5 MHz of superbolts, averaged over 1.5 ms, and measured on the ground by ECLAIR and MTRG, then scaled by WWLLN stroke energy in MJ, as a function of distance from stroke location to ECLAIR and MTRG detecting stations. b Mean-squared electric field of superbolts in space in the VLF range, averaged over a 1 s duration, scaled by the WWLLN stroke energy, as a function of the distance from stroke location to the nearest magnetic footprint (MFP) of the Van Allen Probes, from (blue circle) EFW burst mode and (red square) EMFISIS burst mode. c Same as middle for the mean-squared magnetic field. Regressions give the decay by power laws (color indicates which type of measurements are used).

Ground-to-space transmission factor

Using these empirical fall-off relations with distance, we can rescale backward the space electric PSD and forward propagate the ground electric PSD observed in Fig.  3 to the same altitude (here 300 km where the law of Fig.  4b starts) and take their ratio to obtain a transmission factor from ground to space per frequency for the VLF range reported in Supplementary Table  7 . The transmission factor is ~10 −8 in the VLF range, which represents the lower bound of recent computations 29 , noticing the latter are widely spread over orders of magnitude according to simulation parameters. The transmission factor of the second event observed synchronously is also reported in Supplementary Table  7 , smaller due to the far distance of the superbolt. These two unique and rare synchronous cases we report can serve for modeling the VLF wave emission by ray-tracing, starting from the source in the atmosphere and reaching the magnetic equator in space, which has important applications for radiation belt modeling 30 .

Ground statistics of superbolts

Statistics of all superbolts measured with the ground network are plotted in Fig.  5a –e, along with statistics obtained from all 3349 lightning strokes measured from ECLAIR ground stations in the same period (09/2012-06/2013) (in green) in order to highlight the unique characteristics of superbolts (in red and blue). Superbolt median peak current estimate 31 is 363 kA, ~10 times higher than normal lightning (panel 5a). Fifteen percent of superbolts are positive cloud-to-ground (+CG) flashes, compared with 28% of +CG lightning triggered during the whole campaign. While a typical rise time (Fig.  5b and Supplementary Fig.  8c ) of normal lightning is 1–2 µs (up to 5 µs), superbolts last longer, 5–6 µs (up to 15 µs). The decay time of the ground wave (from maximum to zero) is between 50 and 90 µs for normal negative cloud-to-ground (-CG) lightning, giving a well-known asymmetric shape to the ground wave 5 for normal strokes. On the contrary, superbolts have a fast decay time of 10–20 µs (panel 5c), comparable to the rise time (Fig.  5b and Supplementary Fig.  8c ), leading to a more symmetric ground wave (as seen in Fig.  3f and Supplementary Fig.  7e ). This remarkable symmetry of the discharge, existing, for instance, for narrow bipolar pulses 5 , could help reveal physical differences between superbolts and other lightning. The median of the ground wave electric field (reported at ground distance of 100 km) is +240 V/m to be compared with + /−20 V/m for normal lightning (panel 5d). Median squared electric field, computed over 1.5 ms is 2.6 (V/m) 2 on the ground, about 100 times higher than for normal strokes (panel 5e). We find on average 38% of the total power (2 kHz–5 MHz) is in the VLF range (2–12 kHz) for normal lightning while this percentage reaches 68% for superbolts (cf. distribution in Supplementary Fig.  9a ). This percentage increases as the lightning power increases (Supplementary Fig.  9b ). This suggests that is the longer duration of powerful lightning that populates the lowest frequencies of the VLF range.

Statistics of superbolt ground measurements from (blue) ECLAIR and (red) from both ECLAIR and MTRG stations compared with (green) the normalized statistics of regular lightning flashes measured by ECLAIR ground stations (from 3349 events and normalized to the maximum of superbolt statistics): a peak current estimate, b discharge rise time (time from 50 to 90% of peak), c discharge decay time, from maximum of the first peak to zero, d maximum electric field of the ground wave scaled to 100 km (using fits from Fig.  4 ), and e ground squared electric field, averaged over 1.5 ms. Notable findings are the symmetry of the superbolt’s discharge on the ground ( c , b ), peak current and electric field ~10 times larger than normal lightning ( a , d ), ground mean EM field squared about 100 times larger than for normal lightning ( e ).

Space statistics of superbolts

In space, another remarkable characteristic in these statistics is that superbolts are rare during day time, with 5/66 events occurring from ~9am to ~5 pm local time (Fig.  6a , pink histogram). Yet there is no sensitivity to day/night measured on the ground (6a, black/blue lines). This local time dependence is similar to the one found for non-superbolt lightning-generated waves (cf. second panel of Fig.  4 in ref. 21 ) and supports previous findings that the day time ionosphere makes the propagation of any lightning-generated waves into the magnetosphere more difficult. Superbolts detected in space from local burst-mode measurements are measured at a median satellite L-shell of 1.6 (~4000 km altitude at the equator). The mean [median] distance between WWLLN superbolt location and the closest magnetic footprint of the Van Allen Probes is 5924 km [5023 km]. They have a long-time delay (0.1–0.8 s) that corresponds to propagation time in the Earth-ionosphere waveguide and along field lines in the magnetosphere to the satellite, with some possible reflection between the conjugate points. The time delay, δ t, follows therefore a linear scaling with respect to L-shell, δ t = 0.277L – 0.225 in second, that is established in (panel 6b). Further ray-tracing studies should be able to answer whether this delay is due to ducted wave propagation along field lines in density depletions/enhancements (ducts) or to unducted wave propagation 32 , which is a general open problem of wave propagation 25 , 33 . Of the 10,724 superbolt events identified by WWLLN in 2012–2018, 431 WWLLN-detected superbolts were also captured by EMFISIS lower-resolution survey-mode data between 2012 and 2018. However, Van Allen Probes survey-mode measurements collect 0.5-s long records every 6 s. As superbolts signals in space typically exceed 1-s duration, the survey measurements usually do not contain the entire signal, thus truncating the total measured power. We show in Fig.  6(c, d) that survey-mode superbolt average power (black lines) is statistically larger than normal lightning, but not as powerful as burst-mode determined average power (pink histogram). This artificial bias is revealed by the burst-mode squared electric/magnetic field (pink, Fig.  6 c/ 6d ), which is found to be 10–1000 times more powerful than normal lightning (with global statistics 21 scaled in green for comparison). The three strongest events have a ~250 pT (6 mV/m) wave magnetic (electric) rms amplitude in Fig.  6c , d. The mean magnetic (electric) rms amplitude of the 66 superbolts is 83 pT (873 µV/m) in Fig.  6c , d. In comparison, the mean magnetic (electric) rms amplitudes of lightning-generated waves computed from survey measurements of all types of lightning strokes (possibly including superbolts) is ~83 (~43) times lower, with 1 ± 1.6 pT (19 ± 59 μV/m) 21 .

Superbolts’ local time (in hour) distribution ( a ) and b time delay from ground time to detection time in space versus L-shell ( t  =  αL  +  β ). Statistics of Van Allen Probes c magnetic and d electric field squared, averaged over 1 s, from (pink) burst and (black) survey-mode measurements compared with (green) regular VLF lightning-generated wave distributions 21 . The mean [median] of the magnetic (electric) field squared is 3598 pT 2 (0.40 mV 2 /m 2 ) [80 pT 2 (0.015 mV 2 /m 2 )]. Notable findings are the absence of the superbolt’s electromagnetic signal in space during day times ( a ), a long-time delay of the space signal proportional to L-shell ( b ), ground and space mean EM field squared about 100 times larger than for normal lightning ( c , d ).

The maximum of the burst-mode squared electric/magnetic field within the superbolt time window is provided in Supplementary Fig.  10 . The comparison of Supplementary Fig.  10 with Fig.  6(c, d) shows the peak power exceeds by a factor ~10 (13) the mean magnetic (electric) power. Mean peak superbolt magnetic (electric) amplitude is 0.2 nT (1.9 mV 2 /m 2 ) (Supplementary Fig.  10 ). Peak values are useful for nonlinear computations briefly mentioned below. Intercomparison of superbolt’s electromagnetic power with other natural waves such that whistler-mode hiss waves 20 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , whistler-mode chorus waves 20 , 43 , and ElectroMagnetic Ion Cyclotron (EMIC) waves 44 is left for future work.

Given spatial and temporal coverage of the Van Allen Probes data set, as well as the burst trigger algorithms, these events likely represent (to order-of-magnitude) the maximum power attainable for lightning-driven VLF waves near the Van Allen Probes. Such values may be useful for defining the dynamic range of future wave instruments or as an upper bound on lightning VLF wave power in simulations or numeric calculations. Extremely powerful lightning events including superbolts (>100 pT, representing 0.02% of lightning-generated waves) have been identified as strongly contributing to the global rms magnetic amplitude of lightning-generated waves for L  < 2 (e.g., 44% at L  = 1.1) 21 . These results suggest thus that the tail of the power density distribution of any type of waves (such as whistler-mode or EMIC waves) needs to be derived from, or at least confirmed by, from burst-mode measurements in order not to under-estimate the true wave power that is required for accurate radiation belt modeling (while today most statistical models are built from survey-mode data 21 , 34 , 35 , 37 , 39 , 41 , 42 ). Finally, superbolt’s extreme power is a good candidate of highly powerful waves for which the quasilinear approximation (commonly used to compute wave-particle interactions in the radiation belts 45 , 46 , 47 , 48 , 49 , 50 ) should break 51 , 52 , and to study further various nonlinear wave-particle interaction models 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 .

This study shows simultaneous measurements of a superbolt on the ground and the intense VLF signals in space driven by lightning. Ground and space observations demonstrate how different and extreme superbolts can be compared with normal lightning, for reasons not yet established. This study is a significant characterization of the previously unknown superbolts’ electromagnetic power, that should guide modeling and understanding of lightning electrodynamics, atmospheric discharges, and wave transmission from Earth to space, with applications in remote sensing, and wave modeling in space for radiation belt physics. Simultaneous optical and electromagnetic observations 59 , 60 should be critical to help reveal more mysteries of superbolts.

Ground-based measurements of superbolts

The north Atlantic in western of Europe and the Mediterranean Sea in southern-western of Europe have some of the highest wintertime occurrence rates of superbolts 7 . This is a region covered by Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) ground stations 14 , 15 in France. The ground stations measure electric fields from a few hundred Hertz to 5 MHz 14 (VLF to High Frequency; HF) with vertical dipole whip antennas, at a sampling rate of 12.5 MHz.

The WWLLN network identifies 10,724 superbolts world-wide (gray dots, Supplementary Fig.  1 ) with a radiated energy greater than 1 MJ from synchronized measurements by >7 ground receivers 7 (with a WWLLN residual time of group arrival for all stations of less than 30 μs) for the years 2012–2018, out of 1.5 × 10 9 total strokes detected (see Supplementary Method  2 for the influence of the WWLLN minimum station number detecting a stroke and the residual time on the total number of superbolts). Thus, the occurrence frequency of superbolts in this WWLLN data set is seven events per million CG lightning events, yielding an average of 3.5 superbolt events per day world-wide (with a four times higher probability of occurrence in northern winter), and implying a very low probability to observe them simultaneously from space and on the ground. Among these 10,724 superbolts, 4034 were identified in Europe (Fig.  1 ), of which 384 occurred between 09/2012 and 06/2013, corresponding to a ground measurement campaign (ECLAIR) conducted by CEA. Of these, 368 high-resolution superbolt ground waveforms were recorded during ECLAIR 26 , with 86 of them also detected by the stations of the French lightning location network, Météorage (MTRG) 16 , within 1500 km of the ECLAIR network center (Fig.  1 ). These ground measurements (including WWLLN) provide superbolt occurrence time (with time accuracy <1 ms), geographic location, and WWLLN energy. They also provide ECLAIR high-resolution waveforms with rise and decay times, and ECLAIR and MTRG peak current estimates 31 (see Supplementary Method  1 for more information).

Space measurements of superbolts

In space, we use the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument suite 17 and the Electric Fields and Waves (EFW) instrument 18 on board the two probes (Probe A and Probe B) of the NASA Van Allen Probes spacecraft 19 to measure electric and magnetic wave fields near the magnetic equatorial plane (+/−20° magnetic latitude). The instruments provide similar burst data, but capture records at different times. These ground and space-based measurements are used to study the symmetry of the first ground-wave peak, determine the time it takes for the signal to propagate to the satellite, quantify the loss of signal strength with distance, compute the frequency-dependent transmission of the wave power, and generate statistics (see Supplementary Method  1 for more information).

Superbolt detection and selection

Of the 10,724 WWLLN superbolts, 1143 occurred during a time when Van Allen Probes EFW or EMFISIS were capturing burst data that records electromagnetic waves at high temporal resolution, called the waveform, although most of these waveforms did not measure a superbolt due to the satellite’s location. Only 212 of these burst captures occurred when the Van Allen Probes were at L-shell, L, less than three where most of lightning-generated waves are observed 21 . For facilitating further selection, composite figures (such as Figs.  2 , 3 and Supplementary Figs.  6 and 7 discussed in the article) were generated for each of the 212 superbolts and used to screen them. Among them, 81 were retained because the on board burst system was triggered by identified whistler-mode waves and no unidentified (or other) radio wave power corrupted (partially or entirely) the burst signal. Additional selection criteria were then applied for retaining only clearly identified superbolts: (1) the lightning VLF signal was fully captured by the burst data (uninterrupted); (2) no other lightning flashes mask the superbolt signal (i.e., no lightning of higher or comparable estimated signal power 22 , 23 at the satellite occurred within the burst window); (3) and the distance (direct line), d , from the superbolt location to the magnetic footpoint of the field line on which the satellite sits is <8000 km. Note that although we are requiring that the satellite L is less than three, there is no restriction on the superbolt location. For superbolts with d  > 8000 km, we identified and retained some additional weak signals by hand that satisfied criteria (1) to (2). This process ensures the least possible contamination of the superbolt wave signal by other lightning. At the end of the selection process, only 66 burst captures of superbolt remained (38 from EFW and 28 from EMFISIS, with 1 recorded by both) out of the 1143 candidate events during which burst data was also collected. Among the 66 selected burst-mode signals, 33 were located by WWLLN to be over Europe (cf. Fig.  1 ), and only two of these were simultaneously recorded by ECLAIR, with one too far (9435 km away) from the closest Van Allen Probes magnetic footprint to be clearly identified. For these two events there is high-resolution data available from both the ground and space instrumentation that permits a detailed study linking the superbolt properties on the ground and in space, discussed below. Datasets are summarized in Supplementary Table  1 .

High-resolution power spectral density (PSD) from a selection of six superbolts is shown in Fig.  2 , computed from either the burst-mode electric field (a1–d1) or the ground-based (e1–f1) electric field waveforms. These waveforms (displayed in Supplementary Figs.  2 , 3 , 4 ) were decomposed by Fourier transform to produce electric field PSDs. The respective Van Allen Probes magnetic field PSDs are shown in Supplementary Fig.  5 . Characteristics of all superbolts discussed specifically in the article are gathered in Supplementary Table  2 and 3 . The black line in Fig.  2 (a2–f2) (see also the respective magnetic field intensity in Supplementary Fig.  5 ) represents the evolution of the square of the electric (magnetic) field wave, E 2 in V 2 /m 2 ( B 2 in pT 2 ), a.k.a. the wave electric (magnetic) intensity or squared amplitude or, more commonly called, the wave power, that is the frequency integral of the electric (magnetic) field PSD over the VLF range in space (~2–10 kHz) and (~2 kHz–5 MHz) on the ground.

Data availability

ECLAIR ground waveforms 26 are available at https://zenodo.org/record/3952425 . Météorage data may be ordered from https://www.météorage.com. Van Allen Probes field data are available from the EFW and EMFISIS team websites, which one can link to here: http://rbspgway.jhuapl.edu . The WWLLN data are available from any WWLLN host or may be ordered from links ( http://wwlln.net ). The satellite Situation Center Locator operated online by NASA provides Van Allen Probes trajectories ( https://sscweb.gsfc.nasa.gov/ ).

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Acknowledgements

The authors thank the World Wide Lightning Location Network, a collaboration among over 50 universities and institutions, for providing the lightning location and energy data used in this paper. The work of J.-F.R., T.F., G.S.C., and E.H.L. was performed under the auspices of an agreement between CEA/DAM (Commissariat à l’Energie Atomique, Direction des Applications Militaires) and NNSA/DP (National Nuclear Security Administration, Defense Program) on cooperation on fundamental science. The authors acknowledge the International Space Sciences Institute (ISSI). The work of GSC was supported in part by the Defense Threat Reduction Agency (DTRA). Thanks also to DTRA for supporting a collaborative visit by JFR at Los Alamos National Laboratory in 2018. The work of DM was supported by the National Science Foundation under award 1841011. The authors thank the entire Van Allen Probes team, and especially the EFW and EMFISIS teams for their support.

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J.-F.R. led the study, performed the data analysis, and wrote the manuscript. T.F. set up the CEA ground measurements (ECLAIR), processed the WWLLN, ECLAIR ground, and EFW and EMFISIS burst data, and performed the data analysis. D.M.M. treated the EFW and EMFISIS burst and survey data. E.H.L. contributed to WWLLN data quality check. D.M.M., E.H.L., and G.S.C. contributed to the data analysis. G.B.H. and C.A.K. contributed to the quality check of EMFISIS data and burst PSD computation. J.R.W. contributed to the quality check of EFW data. S.P. provided Météorage data. T.F., D.M.M., E.H.L., G.S.C., G.B.H., C.A.K., and J.R.W. contributed to writing of the manuscript through reviews and edits.

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Ripoll, JF., Farges, T., Malaspina, D.M. et al. Electromagnetic power of lightning superbolts from Earth to space. Nat Commun 12 , 3553 (2021). https://doi.org/10.1038/s41467-021-23740-6

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Lightning impacts edge of space in ways not previously observed

Solar flares jetting out from the sun and thunderstorms generated on Earth impact the planet's ionosphere in different ways, which have implications for the ability to conduct long range communications.

A team of researchers working with data collected by the Incoherent Scatter Radar (ISR) at the Arecibo Observatory, satellites, and lightning detectors in Puerto Rico have for the first time examined the simultaneous impacts of thunderstorms and solar flares on the ionospheric D-region (often referred to as the edge of space).

In the first of its kind analysis, the team determined that solar flares and lightning from thunderstorms trigger unique changes to that edge of space, which is used for long-range communications such the GPS found in vehicles and airplanes.

The work, led by New Mexico Tech assistant professor of physics Caitano L. da Silva was published recently in the journal Scientific Reports , a journal of the Nature Publishing Group.

"These are really exciting results," says da Silva. "One of the key things we showed in the paper is that lightning- and solar flare-driven signatures are completely different. The first tends to create electron density depletions, while the second enhancements (or ionization)."

While the AO radar used in the study is no longer available because of the collapse of AO's telescope in December of 2020, scientists believe that the data they collected and other AO historical data will be instrumental in advancing this work.

"This study helps emphasize that, in order to fully understand the coupling of atmospheric regions, energy input from below (from thunderstorms) into the lower ionosphere needs to be properly accounted for," da Silva says. "The wealth of data collected at AO over the years will be a transformative tool to quantify the effects of lightning in the lower ionosphere."

Better understanding the impact on the Earth's ionosphere will help improve communications.

da Silva worked with a team of researchers at the Arecibo Observatory (AO) in Puerto Rico, a National Science Foundation facility managed by the University of Central Florida under a cooperative agreement. The co-authors are AO Senior Scientist Pedrina Terra, Assistant Director of Science Operations Christiano G. M. Brum and Sophia D. Salazar a student at NMT who spent her 2019 summer at the AO as part of the NSF- supported Research Undergraduate Experience. Salazar completed the initial analysis of the data as part of her internship with the senior scientists' supervision.

"The Arecibo Observatory REU is hands down one of the best experiences I've had so far," says the 21-year-old. "The support and encouragement provided by the AO staff and REU students made the research experience everything that it was. There were many opportunities to network with scientists at AO from all over the world, many of which I would likely never have met without the AO REU."

AO's Terra and Brum worked with Salazar taking her initial data analysis, refining it and providing interpretation for the study.

"Sophia's dedication and her ability to solve problems grabbed our attention from the very first day of the REU program," Brum says.

• Solar Flare
• Northern Lights
• Space Telescopes
• Geomagnetic Storms
• Severe Weather
• Solar flare
• Geomagnetic storm
• Space elevator
• Doppler radar
• Eris (dwarf planet)
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Materials provided by University of Central Florida . Original written by Zenaida Gonzalez Kotala. Note: Content may be edited for style and length.

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• Caitano L. da Silva, Sophia D. Salazar, Christiano G. M. Brum, Pedrina Terra. Survey of electron density changes in the daytime ionosphere over the Arecibo observatory due to lightning and solar flares . Scientific Reports , 2021; 11 (1) DOI: 10.1038/s41598-021-89662-x

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Three ways to travel at (nearly) the speed of light.

Katy Mersmann

1) electromagnetic fields, 2) magnetic explosions, 3) wave-particle interactions.

One hundred years ago today, on May 29, 1919, measurements of a solar eclipse offered verification for Einstein’s theory of general relativity. Even before that, Einstein had developed the theory of special relativity, which revolutionized the way we understand light. To this day, it provides guidance on understanding how particles move through space — a key area of research to keep spacecraft and astronauts safe from radiation.

The theory of special relativity showed that particles of light, photons, travel through a vacuum at a constant pace of 670,616,629 miles per hour — a speed that’s immensely difficult to achieve and impossible to surpass in that environment. Yet all across space, from black holes to our near-Earth environment, particles are, in fact, being accelerated to incredible speeds, some even reaching 99.9% the speed of light.

One of NASA’s jobs is to better understand how these particles are accelerated. Studying these superfast, or relativistic, particles can ultimately help protect missions exploring the solar system, traveling to the Moon, and they can teach us more about our galactic neighborhood: A well-aimed near-light-speed particle can trip onboard electronics and too many at once could have negative radiation effects on space-faring astronauts as they travel to the Moon — or beyond.

Here are three ways that acceleration happens.

Most of the processes that accelerate particles to relativistic speeds work with electromagnetic fields — the same force that keeps magnets on your fridge. The two components, electric and magnetic fields, like two sides of the same coin, work together to whisk particles at relativistic speeds throughout the universe.

In essence, electromagnetic fields accelerate charged particles because the particles feel a force in an electromagnetic field that pushes them along, similar to how gravity pulls at objects with mass. In the right conditions, electromagnetic fields can accelerate particles at near-light-speed.

On Earth, electric fields are often specifically harnessed on smaller scales to speed up particles in laboratories. Particle accelerators, like the Large Hadron Collider and Fermilab, use pulsed electromagnetic fields to accelerate charged particles up to 99.99999896% the speed of light. At these speeds, the particles can be smashed together to produce collisions with immense amounts of energy. This allows scientists to look for elementary particles and understand what the universe was like in the very first fractions of a second after the Big Bang. 

Download related video from NASA Goddard’s Scientific Visualization Studio

Magnetic fields are everywhere in space, encircling Earth and spanning the solar system. They even guide charged particles moving through space, which spiral around the fields.

When these magnetic fields run into each other, they can become tangled. When the tension between the crossed lines becomes too great, the lines explosively snap and realign in a process known as magnetic reconnection. The rapid change in a region’s magnetic field creates electric fields, which causes all the attendant charged particles to be flung away at high speeds. Scientists suspect magnetic reconnection is one way that particles — for example, the solar wind, which is the constant stream of charged particles from the Sun — is accelerated to relativistic speeds.

Those speedy particles also create a variety of side-effects near planets.  Magnetic reconnection occurs close to us at points where the Sun’s magnetic field pushes against Earth’s magnetosphere — its protective magnetic environment. When magnetic reconnection occurs on the side of Earth facing away from the Sun, the particles can be hurled into Earth’s upper atmosphere where they spark the auroras. Magnetic reconnection is also thought to be responsible around other planets like Jupiter and Saturn, though in slightly different ways.

NASA’s Magnetospheric Multiscale spacecraft were designed and built to focus on understanding all aspects of magnetic reconnection. Using four identical spacecraft, the mission flies around Earth to catch magnetic reconnection in action. The results of the analyzed data can help scientists understand particle acceleration at relativistic speeds around Earth and across the universe.

Particles can be accelerated by interactions with electromagnetic waves, called wave-particle interactions. When electromagnetic waves collide, their fields can become compressed. Charged particles bouncing back and forth between the waves can gain energy similar to a ball bouncing between two merging walls.

These types of interactions are constantly occurring in near-Earth space and are responsible for accelerating particles to speeds that can damage electronics on spacecraft and satellites in space. NASA missions, like the Van Allen Probes , help scientists understand wave-particle interactions.

Wave-particle interactions are also thought to be responsible for accelerating some cosmic rays that originate outside our solar system. After a supernova explosion, a hot, dense shell of compressed gas called a blast wave is ejected away from the stellar core. Filled with magnetic fields and charged particles, wave-particle interactions in these bubbles can launch high-energy cosmic rays at 99.6% the speed of light. Wave-particle interactions may also be partially responsible for accelerating the solar wind and cosmic rays from the Sun.

Download this and related videos in HD formats from NASA Goddard’s Scientific Visualization Studio

By Mara Johnson-Groh NASA’s Goddard Space Flight Center , Greenbelt, Md.

ENCYCLOPEDIC ENTRY

Lightning is an electric charge or current. It can come from the clouds to the ground, from cloud to cloud, or from the ground to a cloud.

Earth Science, Meteorology, Geography, Physics

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Lightning is an electric charge or current . It can come from the clouds to the ground, from cloud to cloud, or from the ground to a cloud. Lightning is a product of a planet ’s atmosphere . Raindrops very high up in the sky turn to ice . When many small pieces of these frozen raindrops collide with each other in a thundercloud , they create an electrical charge. After some time, the entire cloud fills with an electrical charge. The negative charges ( electrons ) concentrate at the bottom of the cloud. The positive and neutral charges ( protons ) and neutral charges ( neutrons ) gather at the top of the cloud. Negative charges and positive charges attract each other. Thunderclouds are full of electrical charges connecting with each other. These connections are visible as lightning. On the ground beneath the cloud’s negative charges, positive charges build up. The positive charge on the ground concentrates around anything that protrudes , or sticks up—like trees, telephone poles, blades of grass, even people. The positive charges from these objects reach up higher into the sky. The negative charges in the thundercloud reach lower. Eventually, they touch. When they touch, lightning is created between the two charges. This connection also creates thunder. Thunder is simply the noise lightning makes. The loud boom is caused by the heat of the lightning. When the air gets very, very hot, the heat makes the air explode. Since light travels much, much, faster than sound, you’ll see lightning before you hear thunder.

To figure out how far away a storm is, start counting seconds as soon as you see lightning. Stop when you hear thunder. The number you get divided by five is approximately the number of miles away the storm is. For example, if you see lightning and get to 10 before you hear thunder, the storm is about two miles (3.2 kilometers) away. Lightning Safety All thunderstorms and lightning storms are dangerous . Lightning is very, very hot—hotter than the surface of the sun. It can reach 28,000 degrees Celsius (50,000 degrees Fahrenheit). Lightning is more likely to strike objects that stick up off of the ground, including people. In the U.S., lightning kills an average of 58 people each year. That’s more deaths than are caused by tornadoes and hurricanes . If you hear thunder or see lightning, you may be in danger. If you hear thunder, the storm is nearby. Go inside a safe place. Stay away from open areas, like fields, and tall objects, like trees or telephone poles. Stay away from anything metal, too, like chain-link fences, bikes, and metal shelters. Since water is a great conductor of electricity , you should get out of a pool if you’re swimming and stay away from puddles and any other water. If you’re in an area where there is no shelter, crouch low to the ground, but don’t lay down flat. If you’re in a group, stand at least five meters (15 feet) from anyone else.

Greased Lightning Greased lightning is a description for something that is very fast and very powerful. But even the slipperiest substances, like grease, cant be applied to real lightning, of course!

Imperial Lightning Lightning strikes the iconic American Empire State Building in New York City about 100 times every year.

Make Your Own Lightning The same process that creates lightning is possible to experience at home. Rub your feet on a carpet, then touch a metal doorknob. Do you feel a shock? That's static electricity. Static electricity occurs when an object has too many electrons, giving it a negative charge. The negative charge of your body is attracting the positive charge of the metal in the doorknob. This is a less-dangerous version of the negative charges in a thundercloud attracting the positive charge in the ground beneath.

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5 striking facts versus myths about lightning you should know

Lightning strikes Citibank Ballpark in Midland, Texas. (Image credit: Courtesy of Brian Curran/NOAA National Weather Service)

Lightning is a random act of nature that can strike at any time of the year, most often during summer months.

So far this year, there have been 26 people reported to have been struck by lightning; 12 of those people died .* 

It might be cool to look at from a safe distance, but lightning kills more than 20 people each year in the United States and injures hundreds more — with some survivors suffering lifelong neurological damage. 

One thing that is for certain: No place outside is safe during a thunderstorm. This is why we always say, "When thunder roars, go indoors." 

What else should you know about this electrical wonder of nature? We debunk 5 popular myths with science-backed facts about this dangerous and often misunderstood phenomenon.

1. Myth: A tree can act as sufficient shelter during a thunderstorm.

Fact : No. Standing underneath or near a tree is the second most dangerous place to be during a thunderstorm; the most dangerous is being outside in an open space. An enclosed building with wiring and plumbing is the safest place to be during a storm. Remember: Trees, sheds, picnic shelters, tents or covered porches will not protect you from lightning.

2. Myth: Lightning victims carry an electrical charge. If you touch them, you can be electrocuted .

Fact : Not true. The human body does not store electricity. If you are able to, you should give a lightning victim first aid and/or immediately call 911. This is the most chilling of lightning myths because it could be the difference between life and death. 

3. Myth: If you are trapped outside during a thunderstorm, crouching down will reduce your risk of being struck by lightning.

Fact : No. Crouching down will not make you any safer. If you are stuck outside during a storm, keep moving toward a safe shelter.

4. Myth: Lightning never strikes in one place twice.

Fact : Actually, lightning can, and often does, strike the same place repeatedly — especially if it’s a tall and isolated object. For example, the Empire State Building is hit about 25 times per year offsite link .

5. Myth: Lightning cannot strike in an area if it is not raining and skies are clear.

Fact : Not true. Do not wait until a thunderstorm is immediately overhead and for rain to begin to act. If you can hear thunder, lightning is close enough to pose an immediate threat, even if the sky above you is blue. If thunder roars, seek shelter immediately.

If you are planning a summertime outing, check the forecast before going out or sign up for weather alerts on-the-go . Be sure to postpone outdoor activities if thunderstorms are on the way.

For more, head over to our lightning safety module from NOAA’s National Weather Service. 

____________________

*This number reflects lightning injuries and fatalities that have been certified through May 2020 and are reported preliminary thereafter.

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Lightning explained.

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Lightning is a large-scale natural spark discharge that occurs within the atmosphere or between the atmosphere and the Earth’s surface. On discharge, a highly electrically conductive plasma channel is created within the air, and when current flows within this channel, it rapidly heats the air up to about 25,000°C. The lightning channel is an example of terrestrial plasma in action.

Seeing lightning

Lightning is visible as a flash of blue-white light. The extremely high temperatures generated heat the air molecules to a state of incandescence (white hot) such that they emit a vivid white light. At the same time, nitrogen gas (the dominant gas in the atmosphere) is stimulated to luminesce, producing bright blue-white. The combination of light from luminescence and incandescence gives the bolt of lightning its characteristic colour.

Lightning’s partner

Temperatures in the narrow lightning channel reach about 25,000°C. The surrounding air is rapidly heated, causing it to expand violently at a rate faster than the speed of sound, similar to a sonic boom. At about 10 m out from the channel, it becomes an ordinary sound wave called thunder.

Thunder is effectively exploding air, and when heard close to the lightning channel, it consists of one large bang. At about 1 km away, it is heard as a rumble with several loud claps. Distant thunder has a characteristic low-pitched rumbling sound. However, beyond 16 km, thunder is seldom heard.

Conditions needed for lightning to occur

It is the formation and separation of positive and negative electric charges within the atmosphere that creates the highly intensive electric field needed to support this natural spark discharge that is lightning.

The formation of electric charges in the atmosphere is due mainly to the ionisation of air molecules by cosmic rays. Cosmic rays are high-energy particles such as protons that originate from outside the solar system. On colliding with air molecules, they produce a shower of lighter particles, some of which are charged.

Within a thundercloud, the rapid upward and downward movement of water droplets and ice crystals can separate and concentrate these charges. The negative charges accumulate at the bottom part of t he cloud and the positive charges towards the top.

Lightning production

As the area of negative charge at the base of the thundercloud builds up, it induces a region of positive charge to develop on the ground below. As a result of this, a potential difference or voltage is created across t he clou d-to-ground gap. Once the voltage reaches a certain strength, the air between the base of t he cloud and the ground develops an electrical conductivity. At first a channel, known as a stepped leader, is formed. Although invisible to the naked eye, this allows electrons to move from the cloud to the ground.

It is called a stepped leader because it travels in 50 to 100 m sections, with a slight pause in between, to the ground. As it nears the ground, a positively charged streamer fires upwards from the ground to connect with it. Streamers are most often initiated from tall objects on the ground.

Once connected, electrons from t he cloud c an flow to the ground and positive charges can flow from the ground to th e cloud . It is this flow of charge that is the visible lightning stroke.

After the first discharge, it is possible for another leader to form down the channel. Once again, a visible lightning stoke is seen. This can happen 3–4 times in quick succession . All of this happens in a time interval of about 200 milliseconds.

Monitoring lightning

A worldwide lightning location network (WWLLN, pronounced ‘woollen’) was founded in New Zealand in 2003. Working with the collaboration of scientists from around the world, the network plots lightning discharge locations seconds after they occur.

Around the world, there are about 45 lightning flashes per second. Apart from generating the characteristic blue-white light, radio wave pulses known as sferics are also produced. The frequent crackles heard when tuned into an AM radio station during a thunderstorm are sferics from the lightning discharges.

These sferics are registered at the 60 WWLLN receiving stations around the world and provide a near real-time information dataset. This information is made available to scientists via a high-speed internet connection provided by REANNZ (Research and Education Advanced Network New Zealand).

Red sprites

High above thunderstorm clouds at altitudes between 50–90 km, large-scale electrical discharges can occur. These are triggered by thundercloud-to-ground lightning activity. They appear as fleeting, luminous, red-orange flashes and take on a variety of shapes. Unlike ‘hot plasma’ lightning, they are cold plasma forms somewhat similar to the discharges that occur in a fluorescent tube.

It is because of their fleeting nature, lasting mostly for only milliseconds, and ghost-like appearance that the term ‘sprite’ has been used.

Nature of science

The tale of the 100-year hunt for red sprites is a story of how science works. It is a story illustrating that science, rather than knowing all there is to know, stands barely on the threshold of many more discoveries about our complex and fascinating universe. They were given little more credence than UFO sightings until 1989, when university researchers accidentally captured a red sprite on a low-light video camera.

St Elmo’s fire

In the region between a thundercloud and the ground, a very strong electric field can be set up. There is a huge potential difference (voltage) established between the negative base of t he clou d and the positive ground. When this potential difference reaches a certain value, sharp-pointed ground-based objects are seen to glow, often with a hissing sound.

Because this weather-related occurrence sometimes appeared on ships at sea during thunderstorms, it was given the name ‘St Elmo’s fire’. Saint Elmo is the patron saint of sailors, and in the past, sailors regarded such an event as an omen of bad luck and stormy weather.

St Elmo’s fire is a bright blue or violet glow due to the formation of luminous plasma. It appears like fire in some circumstances coming from sharply pointed objects such as masts, spires, lightning rods and even on aircraft wings.

Related content

Explore the basics of static electricity and electrical charge and electrons, insulators and conductors .

Help your students understand more about lightening with the Viewing and monitoring lightning activity.

Useful links

NASA SciJinks website on lightning with easy-to-read information and good animations.

Lightning article from New World Encyclopedia website that includes information on the history of lightning research including a theory called runaway breakdown, a hypothesises that cosmic rays trigger the process.

Information on ‘ transient luminous events ’ produced by large thunderstorms in the upper atmosphere.

Up-to-date information on worldwide lightning strikes from WWLLN .

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Have we made an object that could travel 1% the speed of light?

University Distinguished Professor of Astronomy, University of Arizona

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Chris Impey receives funding from the National Science Foundation and the Hearst Foundation.

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Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to [email protected] .

Have we made an object that could travel at at least 1% the speed of light? – Anadi, age 14, Jammu and Kashmir, India

Light is fast . In fact, it is the fastest thing that exists, and a law of the universe is that nothing can move faster than light. Light travels at 186,000 miles per second (300,000 kilometers per second) and can go from the Earth to the Moon in just over a second. Light can streak from Los Angeles to New York in less than the blink of an eye.

While 1% of anything doesn’t sound like much, with light, that’s still really fast – close to 7 million miles per hour! At 1% the speed of light, it would take a little over a second to get from Los Angeles to New York. This is more than 10,000 times faster than a commercial jet.

The fastest things ever made

Bullets can go 2,600 mph (4,200 kmh), more than three times the speed of sound. The fastest aircraft is NASA’s X3 jet plane , with a top speed of 7,000 mph (11,200 kph). That sounds impressive, but it’s still only 0.001% the speed of light.

The fastest human-made objects are spacecraft. They use rockets to break free of the Earth’s gravity, which takes a speed of 25,000 mph (40,000 kmh). The spacecraft that is traveling the fastest is NASA’s Parker Solar Probe . After it launched from Earth in 2018, it skimmed the Sun’s scorching atmosphere and used the Sun’s gravity to reach 330,000 mph (535,000 kmh). That’s blindingly fast – yet only 0.05% of the speed of light.

Why even 1% of light speed is hard

What’s holding humanity back from reaching 1% of the speed of light? In a word, energy. Any object that’s moving has energy due to its motion. Physicists call this kinetic energy. To go faster, you need to increase kinetic energy. The problem is that it takes a lot of kinetic energy to increase speed. To make something go twice as fast takes four times the energy. Making something go three times as fast requires nine times the energy, and so on.

For example, to get a teenager who weighs 110 pounds (50 kilograms) to 1% of the speed of light would cost 200 trillion Joules (a measurement of energy). That’s roughly the same amount of energy that 2 million people in the U.S. use in a day.

How fast can we go?

It’s possible to get something to 1% the speed of light, but it would just take an enormous amount of energy. Could humans make something go even faster?

Yes! But engineers need to figure out new ways to make things move in space. All rockets, even the sleek new rockets used by SpaceX and Blue Origins, burn rocket fuel that isn’t very different from gasoline in a car. The problem is that burning fuel is very inefficient.

Other methods for pushing a spacecraft involve using electric or magnetic forces . Nuclear fusion , the process that powers the Sun, is also much more efficient than chemical fuel.

Scientists are researching many other ways to go fast – even warp drives , the faster-than-light travel popularized by Star Trek.

One promising way to get something moving very fast is to use a solar sail. These are large, thin sheets of plastic attached to a spacecraft and designed so that sunlight can push on them, like wind in a normal sail. A few spacecraft have used solar sails to show that they work, and scientists think that a solar sail could propel spacecraft to 10% of the speed of light .

One day, when humanity is not limited to a tiny fraction of the speed of light, we might travel to the stars .

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to [email protected] . Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

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Lightning safety: 10 myths—and the facts

To stay safe in a storm, know the truth about lightning dangers, disasters + preparedness | other insurance topics, in this article, myth #1 – lightning never strikes twice in the same place., myth #2 – lightning only strikes the tallest objects., myth #3 – if you're stuck in a thunderstorm, being under a tree is better than no shelter at all., myth #4 – if you don't see rain or clouds, you're safe., myth #5 – a car's rubber tires will protect you from lightning, myth #6 – if you're outside in a storm, lie flat on the ground., myth #7 – if you touch a lightning victim, you'll be electrocuted., myth #8 – wearing metal on your body attracts lightning., myth #9 – a house will always keep you safe from lightning., myth #10 – surge suppressors can protect a home against lightning..

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“When thunder roars, go indoors!” is a truism that actually holds up. But much of what we think we know about lightning is fiction. Here are some common myths, along with the facts that will keep you and your loved ones safe in a storm.

At any given time on our planet Earth, there are 1,800 thunderstorms in progress—and with them comes lightning. Property damage from lightning is covered by standard homeowners insurance for your home, and the comprehensive portion of an auto policy for your car—but bodily harm from lightning isn't easily remedied.

During a thunderstorm, it's best to take shelter in a house, other structure or a hard-topped, fully enclosed vehicle. But as one of these options may not be available to you, your safety and wellbeing may depend on knowing the difference between these lightning myths and the facts.

• Fact: Lightning often strikes the same place repeatedly, especially if it’s a tall, pointy, isolated object. The Empire State Building was once used as a lightning laboratory because it is hit nearly 25 times per year, and has been known to have been hit up to a dozen times during a single storm.
• Fact: Lightning is indiscriminate and it can find you anywhere. Lightning may hit the ground instead of a tree, cars instead of nearby telephone poles, and parking lots instead of buildings.
• Fact: Sheltering under a tree is just about the worst thing you can do. If lightning does hit the tree, there’s the chance that a “ground charge” will spread out from the tree in all directions. Being underneath a tree is the second leading cause of lightning casualties.
• Fact: Lightning often strikes more than three miles from the thunderstorm, far outside the rain or even the thunderstorm cloud. Though infrequent, “bolts from the blue” have been known to strike areas as distant as 10 miles from their thunderstorm origins, where the skies appear clear.
• Fact: True, being in a car will likely protect you. But most vehicles are actually safe because the metal roof and sides divert lightning around you—the rubber tires have little to do with keeping you safe. Convertibles, motorcycles, bikes, open shelled outdoor recreation vehicles and cars with plastic or fiberglass shells offer no lightning protection at all.
• Fact: Lying flat on the ground makes you more vulnerable to electrocution, not less. Lightning generates potentially deadly electrical currents along the ground in all directions—by lying down, you're providing more potential points on your body to hit.
• Fact: The human body doesn’t store electricity. It is perfectly safe to touch a lightning victim to give them first aid.
• Fact: The presence of metal makes very little difference in determining where lightning will strike. Height, pointy shape and isolation are the dominant factors in whether lightning will strike an object (including you). However, touching or being near metal objects, such as a fence, can be unsafe when thunderstorms are nearby. If lightning does happen to hit one area of the fence—even a long distance away—the metal can conduct the electricity and electrocute you.
• Fact: While a house is the safest place you can be during a storm, just going inside isn’t enough. You must avoid any conducting path leading outside, such as electrical appliances, wires, TV cables, plumbing, metal doors or metal window frames. Don’t stand near a window to watch the lightning. An inside room is generally safe, but a home equipped with a professionally installed lightning protection system is the safest shelter available.
• Fact: Surge arresters and suppressors are important components of a complete lightning protection system, but can do nothing to protect a structure against a direct lightning strike. These items must be installed in conjunction with a lightning protection system to provide whole house protection.

Next steps links: Learn more about protecting your home against lightning damage .

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NASA spacecraft captures glowing green dot on Jupiter caused by a lightning bolt

By Caitlin O'Kane

June 20, 2023 / 9:48 AM EDT / CBS News

An image from Jupiter taken by NASA's JunoCam shows a bright green dot on the planet's north pole. Turns out, the glowing orb is a lightning bolt, NASA says.

While lightning on Earth often comes from water clouds near the equator, clouds containing an ammonia-water solution oftentimes cause lighting near Jupiter's poles, according to NASA. 

Juno started its mission on Jupiter in 2016 and orbited the planet 35 times, capturing images and data. The images taken  by the spacecraft are made public by NASA for people to download and process. 

The image of the lightning strike was captured by Juno on December 30, 2020, when it was about 19,900 miles above Jupiter's cloud tops. It was processed by Kevin M. Gill, who NASA calls a "citizen scientist."

Lightning also occurs on other planets. In 1979, another spacecraft called Voyager 1 captured lightning flashes on Jupiter that were 10 times more powerful than lightning on Earth,  according to NASA . On Saturn, lightning can strike as much as 10 times per second.

Data from the Mars Global Surveyor didn't capture information on lightning, but there were bright flashes during dust storms and some scientists believe craters on Mars could be caused by lightning strikes.

Juno's initial mission was supposed to last five years but NASA has extended it until 2025. The space craft has captured information about Jupiter's interior structure, internal magnetic field, atmosphere, magnetosphere, the dust in its faint rings and and its Great Blue Spot, which is an intense magnetic field near the planet's equator. 

Juno is also flying by Jupiter's moons, which have donut-shaped clouds surrounding them, which the spacecraft will fly through. 

Earlier this year, it was announced that  12 new moons were discovered in Jupiter's atmosphere by astronomers. The moons were seen on telescopes located in Hawaii and Chile in 2021 and 2022. The planet now has a record 92 moons.

Caitlin O'Kane is a New York City journalist who works on the CBS News social media team as a senior manager of content and production. She writes about a variety of topics and produces "The Uplift," CBS News' streaming show that focuses on good news.

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What is the speed of light?

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The speed of light traveling through a vacuum is exactly 299,792,458 meters (983,571,056 feet) per second. That's about 186,282 miles per second — a universal constant known in equations as "c," or light speed. 

According to physicist Albert Einstein 's theory of special relativity , on which much of modern physics is based, nothing in the universe can travel faster than light. The theory states that as matter approaches the speed of light, the matter's mass becomes infinite. That means the speed of light functions as a speed limit on the whole universe . The speed of light is so immutable that, according to the U.S. National Institute of Standards and Technology , it is used to define international standard measurements like the meter (and by extension, the mile, the foot and the inch). Through some crafty equations, it also helps define the kilogram and the temperature unit Kelvin .

But despite the speed of light's reputation as a universal constant, scientists and science fiction writers alike spend time contemplating faster-than-light travel. So far no one's been able to demonstrate a real warp drive, but that hasn't slowed our collective hurtle toward new stories, new inventions and new realms of physics.

Related: Special relativity holds up to a high-energy test

A l ight-year is the distance that light can travel in one year — about 6 trillion miles (10 trillion kilometers). It's one way that astronomers and physicists measure immense distances across our universe.

Light travels from the moon to our eyes in about 1 second, which means the moon is about 1 light-second away. Sunlight takes about 8 minutes to reach our eyes, so the sun is about 8 light minutes away. Light from Alpha Centauri , which is the nearest star system to our own, requires roughly 4.3 years to get here, so Alpha Centauri is 4.3 light-years away.

"To obtain an idea of the size of a light-year, take the circumference of the Earth (24,900 miles), lay it out in a straight line, multiply the length of the line by 7.5 (the corresponding distance is one light-second), then place 31.6 million similar lines end to end," NASA's Glenn Research Center says on its website . "The resulting distance is almost 6 trillion (6,000,000,000,000) miles!"

Stars and other objects beyond our solar system lie anywhere from a few light-years to a few billion light-years away. And everything astronomers "see" in the distant universe is literally history. When astronomers study objects that are far away, they are seeing light that shows the objects as they existed at the time that light left them. 

This principle allows astronomers to see the universe as it looked after the Big Bang , which took place about 13.8 billion years ago. Objects that are 10 billion light-years away from us appear to astronomers as they looked 10 billion years ago — relatively soon after the beginning of the universe — rather than how they appear today.

Related: Why the universe is all history

Speed of light FAQs answered by an expert

We asked Rob Zellem, exoplanet-hunter and staff scientist at NASA's Jet Propulsion Lab, a few frequently asked questions about the speed of light. 

Dr. Rob Zellem is a staff scientist at NASA's Jet Propulsion Laboratory, a federally funded research and development center operated by the California Institute of Technology. Rob is the project lead for Exoplanet Watch, a citizen science project to observe exoplanets, planets outside of our own solar system, with small telescopes. He is also the Science Calibration lead for the Nancy Grace Roman Space Telescope's Coronagraph Instrument, which will directly image exoplanets. 

What is faster than the speed of light?

Nothing! Light is a "universal speed limit" and, according to Einstein's theory of relativity, is the fastest speed in the universe: 300,000 kilometers per second (186,000 miles per second). 

Is the speed of light constant?

The speed of light is a universal constant in a vacuum, like the vacuum of space. However, light *can* slow down slightly when it passes through an absorbing medium, like water (225,000 kilometers per second = 140,000 miles per second) or glass (200,000 kilometers per second = 124,000 miles per second). 

Who discovered the speed of light?

One of the first measurements of the speed of light was by Rømer in 1676 by observing the moons of Jupiter . The speed of light was first measured to high precision in 1879 by the Michelson-Morley Experiment. 

How do we know the speed of light?

Rømer was able to measure the speed of light by observing eclipses of Jupiter's moon Io. When Jupiter was closer to Earth, Rømer noted that eclipses of Io occurred slightly earlier than when Jupiter was farther away. Rømer attributed this effect due the time it takes for light to travel over the longer distance when Jupiter was farther from the Earth. 

How did we learn the speed of light?

As early as the 5th century BC, Greek philosophers like Empedocles and Aristotle disagreed on the nature of light speed. Empedocles proposed that light, whatever it was made of, must travel and therefore, must have a rate of travel. Aristotle wrote a rebuttal of Empedocles' view in his own treatise, On Sense and the Sensible , arguing that light, unlike sound and smell, must be instantaneous. Aristotle was wrong, of course, but it would take hundreds of years for anyone to prove it. 

In the mid 1600s, the Italian astronomer Galileo Galilei stood two people on hills less than a mile apart. Each person held a shielded lantern. One uncovered his lantern; when the other person saw the flash, he uncovered his too. But Galileo's experimental distance wasn't far enough for his participants to record the speed of light. He could only conclude that light traveled at least 10 times faster than sound.

In the 1670s, Danish astronomer Ole Rømer tried to create a reliable timetable for sailors at sea, and according to NASA , accidentally came up with a new best estimate for the speed of light. To create an astronomical clock, he recorded the precise timing of the eclipses of Jupiter's moon , Io, from Earth . Over time, Rømer observed that Io's eclipses often differed from his calculations. He noticed that the eclipses appeared to lag the most when Jupiter and Earth were moving away from one another, showed up ahead of time when the planets were approaching and occurred on schedule when the planets were at their closest or farthest points. This observation demonstrated what we today know as the Doppler effect, the change in frequency of light or sound emitted by a moving object that in the astronomical world manifests as the so-called redshift , the shift towards "redder", longer wavelengths in objects speeding away from us. In a leap of intuition, Rømer determined that light was taking measurable time to travel from Io to Earth. 

Rømer used his observations to estimate the speed of light. Since the size of the solar system and Earth's orbit wasn't yet accurately known, argued a 1998 paper in the American Journal of Physics , he was a bit off. But at last, scientists had a number to work with. Rømer's calculation put the speed of light at about 124,000 miles per second (200,000 km/s).

In 1728, English physicist James Bradley based a new set of calculations on the change in the apparent position of stars caused by Earth's travels around the sun. He estimated the speed of light at 185,000 miles per second (301,000 km/s) — accurate to within about 1% of the real value, according to the American Physical Society .

Two new attempts in the mid-1800s brought the problem back to Earth. French physicist Hippolyte Fizeau set a beam of light on a rapidly rotating toothed wheel, with a mirror set up 5 miles (8 km) away to reflect it back to its source. Varying the speed of the wheel allowed Fizeau to calculate how long it took for the light to travel out of the hole, to the adjacent mirror, and back through the gap. Another French physicist, Leon Foucault, used a rotating mirror rather than a wheel to perform essentially the same experiment. The two independent methods each came within about 1,000 miles per second (1,609 km/s) of the speed of light.

Another scientist who tackled the speed of light mystery was Poland-born Albert A. Michelson, who grew up in California during the state's gold rush period, and honed his interest in physics while attending the U.S. Naval Academy, according to the University of Virginia . In 1879, he attempted to replicate Foucault's method of determining the speed of light, but Michelson increased the distance between mirrors and used extremely high-quality mirrors and lenses. Michelson's result of 186,355 miles per second (299,910 km/s) was accepted as the most accurate measurement of the speed of light for 40 years, until Michelson re-measured it himself. In his second round of experiments, Michelson flashed lights between two mountain tops with carefully measured distances to get a more precise estimate. And in his third attempt just before his death in 1931, according to the Smithsonian's Air and Space magazine, he built a mile-long depressurized tube of corrugated steel pipe. The pipe simulated a near-vacuum that would remove any effect of air on light speed for an even finer measurement, which in the end was just slightly lower than the accepted value of the speed of light today. 

Michelson also studied the nature of light itself, wrote astrophysicist Ethan Siegal in the Forbes science blog, Starts With a Bang . The best minds in physics at the time of Michelson's experiments were divided: Was light a wave or a particle? 

Michelson, along with his colleague Edward Morley, worked under the assumption that light moved as a wave, just like sound. And just as sound needs particles to move, Michelson and Morley and other physicists of the time reasoned, light must have some kind of medium to move through. This invisible, undetectable stuff was called the "luminiferous aether" (also known as "ether"). 

Though Michelson and Morley built a sophisticated interferometer (a very basic version of the instrument used today in LIGO facilities), Michelson could not find evidence of any kind of luminiferous aether whatsoever. Light, he determined, can and does travel through a vacuum.

"The experiment — and Michelson's body of work — was so revolutionary that he became the only person in history to have won a Nobel Prize for a very precise non-discovery of anything," Siegal wrote. "The experiment itself may have been a complete failure, but what we learned from it was a greater boon to humanity and our understanding of the universe than any success would have been!"

Special relativity and the speed of light

Einstein's theory of special relativity unified energy, matter and the speed of light in a famous equation: E = mc^2. The equation describes the relationship between mass and energy — small amounts of mass (m) contain, or are made up of, an inherently enormous amount of energy (E). (That's what makes nuclear bombs so powerful: They're converting mass into blasts of energy.) Because energy is equal to mass times the speed of light squared, the speed of light serves as a conversion factor, explaining exactly how much energy must be within matter. And because the speed of light is such a huge number, even small amounts of mass must equate to vast quantities of energy.

In order to accurately describe the universe, Einstein's elegant equation requires the speed of light to be an immutable constant. Einstein asserted that light moved through a vacuum, not any kind of luminiferous aether, and in such a way that it moved at the same speed no matter the speed of the observer. 

Think of it like this: Observers sitting on a train could look at a train moving along a parallel track and think of its relative movement to themselves as zero. But observers moving nearly the speed of light would still perceive light as moving away from them at more than 670 million mph. (That's because moving really, really fast is one of the only confirmed methods of time travel — time actually slows down for those observers, who will age slower and perceive fewer moments than an observer moving slowly.)

In other words, Einstein proposed that the speed of light doesn't vary with the time or place that you measure it, or how fast you yourself are moving. 

Therefore, objects with mass cannot ever reach the speed of light. If an object ever did reach the speed of light, its mass would become infinite. And as a result, the energy required to move the object would also become infinite: an impossibility.

That means if we base our understanding of physics on special relativity (which most modern physicists do), the speed of light is the immutable speed limit of our universe — the fastest that anything can travel. 

What goes faster than the speed of light?

Although the speed of light is often referred to as the universe's speed limit, the universe actually expands even faster. The universe expands at a little more than 42 miles (68 kilometers) per second for each megaparsec of distance from the observer, wrote astrophysicist Paul Sutter in a previous article for Space.com . (A megaparsec is 3.26 million light-years — a really long way.) 

In other words, a galaxy 1 megaparsec away appears to be traveling away from the Milky Way at a speed of 42 miles per second (68 km/s), while a galaxy two megaparsecs away recedes at nearly 86 miles per second (136 km/s), and so on. 

"At some point, at some obscene distance, the speed tips over the scales and exceeds the speed of light, all from the natural, regular expansion of space," Sutter explained. "It seems like it should be illegal, doesn't it?"

Special relativity provides an absolute speed limit within the universe, according to Sutter, but Einstein's 1915 theory regarding general relativity allows different behavior when the physics you're examining are no longer "local."

"A galaxy on the far side of the universe? That's the domain of general relativity, and general relativity says: Who cares! That galaxy can have any speed it wants, as long as it stays way far away, and not up next to your face," Sutter wrote. "Special relativity doesn't care about the speed — superluminal or otherwise — of a distant galaxy. And neither should you."

Does light ever slow down?

Light in a vacuum is generally held to travel at an absolute speed, but light traveling through any material can be slowed down. The amount that a material slows down light is called its refractive index. Light bends when coming into contact with particles, which results in a decrease in speed.

For example, light traveling through Earth's atmosphere moves almost as fast as light in a vacuum, slowing down by just three ten-thousandths of the speed of light. But light passing through a diamond slows to less than half its typical speed, PBS NOVA reported. Even so, it travels through the gem at over 277 million mph (almost 124,000 km/s) — enough to make a difference, but still incredibly fast.

Light can be trapped — and even stopped — inside ultra-cold clouds of atoms, according to a 2001 study published in the journal Nature . More recently, a 2018 study published in the journal Physical Review Letters proposed a new way to stop light in its tracks at "exceptional points," or places where two separate light emissions intersect and merge into one.

Researchers have also tried to slow down light even when it's traveling through a vacuum. A team of Scottish scientists successfully slowed down a single photon, or particle of light, even as it moved through a vacuum, as described in their 2015 study published in the journal Science . In their measurements, the difference between the slowed photon and a "regular" photon was just a few millionths of a meter, but it demonstrated that light in a vacuum can be slower than the official speed of light. 

Can we travel faster than light?

— Spaceship could fly faster than light

— Here's what the speed of light looks like in slow motion

— Why is the speed of light the way it is?

Science fiction loves the idea of "warp speed." Faster-than-light travel makes countless sci-fi franchises possible, condensing the vast expanses of space and letting characters pop back and forth between star systems with ease. 

But while faster-than-light travel isn't guaranteed impossible, we'd need to harness some pretty exotic physics to make it work. Luckily for sci-fi enthusiasts and theoretical physicists alike, there are lots of avenues to explore.

All we have to do is figure out how to not move ourselves — since special relativity would ensure we'd be long destroyed before we reached high enough speed — but instead, move the space around us. Easy, right? 

One proposed idea involves a spaceship that could fold a space-time bubble around itself. Sounds great, both in theory and in fiction.

"If Captain Kirk were constrained to move at the speed of our fastest rockets, it would take him a hundred thousand years just to get to the next star system," said Seth Shostak, an astronomer at the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, California, in a 2010 interview with Space.com's sister site LiveScience . "So science fiction has long postulated a way to beat the speed of light barrier so the story can move a little more quickly."

Without faster-than-light travel, any "Star Trek" (or "Star War," for that matter) would be impossible. If humanity is ever to reach the farthest — and constantly expanding — corners of our universe, it will be up to future physicists to boldly go where no one has gone before.

Additional resources

For more on the speed of light, check out this fun tool from Academo that lets you visualize how fast light can travel from any place on Earth to any other. If you’re more interested in other important numbers, get familiar with the universal constants that define standard systems of measurement around the world with the National Institute of Standards and Technology . And if you’d like more on the history of the speed of light, check out the book " Lightspeed: The Ghostly Aether and the Race to Measure the Speed of Light " (Oxford, 2019) by John C. H. Spence.

Aristotle. “On Sense and the Sensible.” The Internet Classics Archive, 350AD. http://classics.mit.edu/Aristotle/sense.2.2.html .

D’Alto, Nick. “The Pipeline That Measured the Speed of Light.” Smithsonian Magazine, January 2017. https://www.smithsonianmag.com/air-space-magazine/18_fm2017-oo-180961669/ .

Fowler, Michael. “Speed of Light.” Modern Physics. University of Virginia. Accessed January 13, 2022. https://galileo.phys.virginia.edu/classes/252/spedlite.html#Albert%20Abraham%20Michelson .

Giovannini, Daniel, Jacquiline Romero, Václav Potoček, Gergely Ferenczi, Fiona Speirits, Stephen M. Barnett, Daniele Faccio, and Miles J. Padgett. “Spatially Structured Photons That Travel in Free Space Slower than the Speed of Light.” Science, February 20, 2015. https://www.science.org/doi/abs/10.1126/science.aaa3035 .

Goldzak, Tamar, Alexei A. Mailybaev, and Nimrod Moiseyev. “Light Stops at Exceptional Points.” Physical Review Letters 120, no. 1 (January 3, 2018): 013901. https://doi.org/10.1103/PhysRevLett.120.013901 . 

Hazen, Robert. “What Makes Diamond Sparkle?” PBS NOVA, January 31, 2000. https://www.pbs.org/wgbh/nova/article/diamond-science/ . 

“How Long Is a Light-Year?” Glenn Learning Technologies Project, May 13, 2021. https://www.grc.nasa.gov/www/k-12/Numbers/Math/Mathematical_Thinking/how_long_is_a_light_year.htm . 

American Physical Society News. “July 1849: Fizeau Publishes Results of Speed of Light Experiment,” July 2010. http://www.aps.org/publications/apsnews/201007/physicshistory.cfm . 

Liu, Chien, Zachary Dutton, Cyrus H. Behroozi, and Lene Vestergaard Hau. “Observation of Coherent Optical Information Storage in an Atomic Medium Using Halted Light Pulses.” Nature 409, no. 6819 (January 2001): 490–93. https://doi.org/10.1038/35054017 . 

NIST. “Meet the Constants.” October 12, 2018. https://www.nist.gov/si-redefinition/meet-constants . 

Ouellette, Jennifer. “A Brief History of the Speed of Light.” PBS NOVA, February 27, 2015. https://www.pbs.org/wgbh/nova/article/brief-history-speed-light/ . 

Shea, James H. “Ole Ro/Mer, the Speed of Light, the Apparent Period of Io, the Doppler Effect, and the Dynamics of Earth and Jupiter.” American Journal of Physics 66, no. 7 (July 1, 1998): 561–69. https://doi.org/10.1119/1.19020 . 

Siegel, Ethan. “The Failed Experiment That Changed The World.” Forbes, April 21, 2017. https://www.forbes.com/sites/startswithabang/2017/04/21/the-failed-experiment-that-changed-the-world/ . 

Stern, David. “Rømer and the Speed of Light,” October 17, 2016. https://pwg.gsfc.nasa.gov/stargaze/Sun4Adop1.htm . 

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Vicky Stein is a science writer based in California. She has a bachelor's degree in ecology and evolutionary biology from Dartmouth College and a graduate certificate in science writing from the University of California, Santa Cruz (2018). Afterwards, she worked as a news assistant for PBS NewsHour, and now works as a freelancer covering anything from asteroids to zebras. Follow her most recent work (and most recent pictures of nudibranchs) on Twitter. 

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Learn about our planet!

Can lightning travel through a vacuum?

Lightning as we know it in air cannot happen in vacuum because lightening depends crucially on the generation of positive ions and negative electrons by ionization of molecules of the air in high electric fields (and eventually high temperatures) and the ensuing impact ionization typical for a gas discharge.

Electrons can jump from one surface to another in vacuum, but they require a larger voltage to do so than if there were air in between the surfaces. If you define this to be lightning, rather than the resulting breakdown of air molecules that normally occurs, then yes lightning can occur in vacuum.

This is what our research found. because of this light does not require a medium for propagation. They can travel through a vacuum. Was this answer helpful?, and thank you. Your Feedback will Help us Serve you better.

Lightning can travel through any metal wires or bars in concrete walls or flooring. Even though your home is a safe shelter during a lightning storm, you may still be at risk.

Could Lightning come from space?

Not in ‘Deep Space’ as it’s commonly viewed, which is basically a whole lot of nothing. Lightning is effectively a large discharge of static electricity. With nothing around, there’s nothing to build up a charge. Which is by no means to suggest Earth is the only place with large static discharges.

Is it possible to get lightning in space?

Yes, lightning occurs in space . It occurs in the clouds of planets and in molecular clouds in space as well from other phenomena in space. These colorful flashes are called blue jets and they can stretch 30 miles into the stratosphere.

Another common query is “Does Lightning take up space?”.

One source argued that the Empire State Building was once used as a lightning laboratory because it is hit nearly 25 times per year, and has been known to have been hit up to a dozen times during a single storm. Myth #2 – Lightning only strikes the tallest objects. Fact: Lightning is indiscriminate and it can find you anywhere. Lightning may hit the ground instead.

Does Lightning come from Outer Space?

This idea is not new: More than 20 years ago, physicist Alex Gurevich at the Russian Academy of Sciences in Moscow suggested lightning might be initiated by cosmic rays from outer space. These particles strike Earth with gargantuan amounts of energy surpassing anything the most powerful atom smashers on the planet are capable of.

Electrons, flowing as the lightning propagates, are free electrons, not bound to nuclei, and if they accelerate, they can emit visible light. Thus lightning would be possible in vacuum, and it could be visible too. Is lightning an example of energy emision from accelerated charge? The sort answer is no.

Is it safe to be inside during a lightning storm?

Even though your home is a safe shelter during a lightning storm, you may still be at risk. About one-third of lightning-strike injuries occur indoors. Here are some tips to keep safe and reduce your risk of being struck by lightning while indoors., and avoid water.

Basically, lightning is visible because of the heat that is generated in the molecules of air, and the flow of the current is possible only because air atoms are ionized by the electric field, and the air molecules, in a plasma form, have atoms in excited state, and when these relax, they emit visible light.

Can a grenade explode in a vacuum?

First, in the instance of a grenade, frag or High explosive, it would and could theoretically explode in a vacuum, however, it most definitely would not look like the movies or make any sound in space. Since it needs no outside sources of oxygen to explode, it would start of like a normal earthly explosive reaction.

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No Man's Sky Player Discovers Hilarious New Method of Space Travel

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No Man's Sky Releases New Adrift Update

Stray is finally coming to the nintendo switch, but there's a catch, wuthering waves set to surpass genshin impact's revenue just two months after launch.

• A player discovers they can travel to space in No Man's Sky by sitting on a couch on a gas vent.
• Players can break the game by launching themselves to other planets with the "space chair" glitch.
• Despite the bugs, fans find inventive ways to exploit the glitches.

A bizarre No Man's Sky glitch discovered by one player has allowed them to establish a way of venturing into the final frontier using nothing more than a natural gas vent and a well-placed couch. While No Man's Sky has seen countless bugs come and go throughout the nearly eight years that have passed since its launch, veteran members of the community continue to discover strange new glitches and methods of exploiting them to this day.

While widely considered to be a fairly buggy game, particularly after the state of its launch in 2016, No Man's Sky has seen numerous fixes and drastic improvements across the many updates the game has received over the years. Still, these very content updates and additions often pave the way for new bugs for players to discover as well, but even so, No Man's Sky fans consistently prove masterful at taking advantage of such oddities, with many occasionally going as far as using them to add new features to their bases.

No Man’s Sky releases an update that puts players in a universe devoid of all intelligent life, making them feel truly alone.

This is exactly what was recently done by one inventive fan known online as spaceandstuff_NMS in order to create an entirely new and starship-free method of space travel in No Man's Sky . Demonstrated in a variety of clips that the player has shared across social media, this technique relies on the crystal sulphide gas vents which can be found in No Man's Sky 's aquatic environments , meaning that players will need to be on a planet with liquid water if they hope to recreate the bug themselves. As the clip shows, placing a couch or chair directly on top of any such gas vent and sitting in it will cause the player to be jettisoned directly upwards when the vent erupts, with the player maintaining a seemingly permanent skyward velocity.

How This 'Space Chair' Can Have Unexpected Uses for No Man's Sky Players

Thanks to the fact that players can seamlessly transition from a planetary surface to space itself, players will eventually break orbit by doing this. Unsurprisingly, this lets players break the game in quite a few ways, though it is completely possible for No Man's Sky players to land on and access their freighters in space if they set up the launch correctly. If done perfectly, there's nothing stopping players from launching themselves to other planets in a star system, as was demonstrated in a YouTube video posted by spaceandstuff_NMS which gives fans more information on how to replicate this glitch for themselves.

Despite the various unusual and often outright hilarious bugs that players have encountered in No Man's Sky , this one definitely stands out as one of the more unique exploits fans have discovered in the past few years. It's quite likely a bug that has been present in-game since as far back as the addition of crystal sulphide vents with The Abyss update in 2018, but it has otherwise gone unnoticed by the community until now.

No Man's Sky

No Man's Sky is a space exploration game that is procedurally generated. After a rocky launch, develop Hello Games has spent years adding and adjusting the game to make it the arguable masterpiece it is today.

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Short Wave: Space Camp

In our wildest dreams, we’re able to warp across the universe to witness its mysteries and discover its quirks up close. In this series, we do exactly that: Regina and Emily blast off into space and travel to the most distant, weirdest parts of our universe — from stars to black holes.

• About Short Wave
• Meet the team
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• Check out Short Wave+

From the physics of g-force to weightlessness: How it feels to launch into space

Regina G. Barber

Emily Kwong

Berly McCoy

Rebecca Ramirez

Astronaut Wendy B. Lawrence was aboard the the Space Shuttle Endeavour for the STS-67/ASTRO-2 mission when it launched March 2nd, 1995. NASA hide caption

Astronaut Wendy B. Lawrence was aboard the the Space Shuttle Endeavour for the STS-67/ASTRO-2 mission when it launched March 2nd, 1995.

This story is part of Short Wave's series Space Camp about all the weird, wonderful things happening in the universe. Check out the  rest of the series .

What does it take to launch into space?

Other than money, hard work and many moving parts, the answer is science ! This summer, NPR science podcast Short Wave is launching Space Camp, a series about all the weird and wonderful things in our universe. We start with how to get to outer space in the first place.

Rockets and Isaac Newton

It mostly goes without saying, but for a person to get to outer space, they need to be in some sort of spacecraft attached to a rocket.

That rocket shoots out exhaust when it leaves the launch pad. That exhaust is shooting towards the launchpad. This is where Isaac Newton's third law of motion comes into action. This law says that "for every action there is an equal and opposite reaction." So, as the exhaust pushes downward, it creates an upward force, letting the rocket shoot skyward.

Here, Walter Lewin, formerly a professor of MIT, completes a common demonstration of Newton's third law of motion, as part of his farewell lecture.

A good example on a smaller scale is a common physics demonstration where someone holds a fire extinguisher while sitting on something with wheels. Like in this video, as the extinguisher fires, the person goes the opposite direction.

The exhaust from a rocket launching into space does the same thing.

The rocket has to go really fast because it needs to overcome the curvature of spacetime itself. The fabric of our universe, called spacetime, can be thought of as a bendable sheet. The mass of Earth makes the flat fabric of spacetime curve inward in a funnel-like shape. Moving up the funnel — thereby escaping Earth's gravity — is more difficult than moving down.

This illustration explains gravitational force, also known as "g-force." It is one of the four fundamental forces in the universe, and is seen bending spacetime amid the mass of Earth. NASA hide caption

This illustration explains gravitational force, also known as "g-force." It is one of the four fundamental forces in the universe, and is seen bending spacetime amid the mass of Earth.

G-forces and why floating is falling

When those rockets blast off, astronauts experience intense g-forces.

G-forces come from when your body experiences acceleration. When you're just sitting or walking around on Earth, you're probably not noticing them — even though there's always the regular pull of Earth's gravity, which is 1 G.

You're more likely to notice them when you're doing something like going up in an elevator pretty fast. Then, you feel heavier.

Explore the full series: Space Camp

But the heaviness of being in a fast elevator is nothing compared to what astronauts experience during a launch. Retired Navy Captain and former NASA astronaut Wendy Lawrence recalled the feeling of intense g-forces to NPR in a recent interview.

"I remember on my first flight thinking, 'Oh, my gosh, somebody just sat down on my chest,'" she says. "I tried to see if I could put my arm out in front of me ... and like, 'Wow, I cannot hold it out there against this tremendous power and acceleration being produced by this amazing space vehicle.'"

Astronaut Wendy B. Lawrence, flight engineer and mission specialist for STS-67, scribbles notes on the margin of a checklist while monitoring an experiment on the Space Shuttle Endeavour's mid-deck. MSFC/NASA hide caption

Astronaut Wendy B. Lawrence, flight engineer and mission specialist for STS-67, scribbles notes on the margin of a checklist while monitoring an experiment on the Space Shuttle Endeavour's mid-deck.

Pretty quickly, that experience changes. Once rockets detach from the spaceship, that force pushing the astronauts into their seats is gone. They start to float under their seatbelts.

They feel what is commonly called weightlessness.

But gravity isn't gone. Even on the International Space Station, astronauts experience microgravity.

You can get a small taste of this feeling on Earth. There are amusement park rides that shoot up — causing riders to feel heavy — and then drop riders. During that drop, the riders feel weightless even though they're actually falling. In physics this is called freefall. All the astronauts in the International Space Station are technically falling very slowly, which is why they feel weightless.

Captain Lawrence says it's an amazing experience. "You just relax," she recalls. "You're suspended right there in the middle of the air, and you want park yourself in front of a window and float in front of it and watch the world go by."

To orbit is to fall and miss Earth

It turns out that orbiting, as astronauts aboard the International Space Station do, is falling. Specifically, it's towards Earth.

Newton had a series of thought experiments to explain this idea.

Scenario 1: Imagine you're standing on flat ground. Now imagine that you shoot a cannonball horizontally from your spot on the ground. In this scenario, the cannon ball will travel horizontally for a while before it starts to fall along a curved path. This is projectile motion.

Scenario 2: You shoot this same cannonball horizontally — from the top of a very tall mountain. In this case, the ball would hit the ground even farther away because it had farther to fall and would have been in the air longer. If you shoot the cannonball out at a higher velocity, it would travel even farther . That curved path is getting more and more stretched.

Scenario 3: With a high enough launch speed you can get the cannonball to fall at a curved path that matches the curvature of Earth. Since the curvatures match, the cannon ball keeps missing Earth. This is what it means to have something in orbit. The cannonball falls but never reaches the ground.

Next up: Short Wave Space Camp: Pluto

Now if we get out of Earth's orbit and to the end of our solar system, we will pass the beloved once-planet Pluto. Why are there only eight planets in our solar system? What does it mean that Pluto was downgraded to a dwarf planet all those years ago? We also explain why Pluto's geology surprised scientists.

More from Short Wave

Have other space stories you want us to cover? Email us at [email protected] .

Listen to Short Wave on Spotify , Apple Podcasts and Google Podcasts .

Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave .

This episode was produced by Berly McCoy, edited by Rebecca Ramirez and fact checked by Regina Barber, Emily Kwong and Rebecca. Gilly Moon was the audio engineer.

• International Space Station

Scientists Release Largest Trove of Data on How Space Travel Affects the Human Body

A collection of 44 new studies, largely based on a short-duration tourist trip in 2021, provides insight into the health effects of traveling to space

Will Sullivan

Daily Correspondent

More and more humans are traveling to space. Several missions in 2021 took private citizens on tourist flights. Last month, six people flew to the edge of Earth’s atmosphere and back. NASA plans to put astronauts back on the moon later this decade, and SpaceX recently tested a rocket it hopes will one day carry humans to Mars.

With even more ambitious crewed flights on the horizon, scientists want to better understand the effects that space’s stressors—such as exposure to radiation and a lack of gravity—have on the human body. Now, a newly released set of 44 papers and troves of data, called the Space Omics and Medical Atlas (SOMA), aims to do just that.

SOMA is the largest collection of data on aerospace medicine and space biology ever compiled. It dramatically expands the amount of information available on how the human body changes during spaceflight. And the first studies to come out of this project improve scientists’ understanding of how space travel affects human health.

“This will allow us to be better prepared when we’re sending humans into space for whatever reason,” Allen Liu , mechanical engineer at the University of Michigan who is not involved in the project, tells Adithi Ramakrishnan of the Associated Press (AP).

Much of the new atlas is based on data collected from the four members of the Inspiration4 mission , a space tourism flight that sent four civilians on a three-day trip to low-Earth orbit in September 2021. The findings suggest people on short-term flights experience some of the same health impacts that astronauts face on long-term trips to space.

“We don’t yet fully understand all of the risks” of long-duration space travel, Amy McGuire , a biomedical ethicist at Baylor College of Medicine who did not contribute to the work, says to Science ’s Ramin Skibba. “This is also why it is so important that early space tourists participate in research.”

Space travel poses a number of risks to health. Without Earth’s atmosphere and magnetic field to protect them, astronauts are exposed to space radiation , which can increase their risk for cancer and degenerative diseases. Fluid shifts into astronauts’ heads when they are experiencing weightlessness, which can contribute to vision problems , headaches and changes in the structure of the brain . The microgravity environment can also lead to a loss of bone density and atrophied muscles , prompting long-haul astronauts to adopt specific exercise regimens .

But on top of those known risks, the new research highlights other potential issues. One study published Tuesday in the journal Nature Communications found that mice exposed to a dose of radiation meant to simulate a round trip to Mars experienced kidney damage and dysfunction. Human travelers might need to be on dialysis on the way back from the Red Planet if they were not protected from this radiation, writes the Guardian ’s Ian Sample.

“It’s likely to be a serious issue,” Stephen Walsh , a co-author of the study and clinician scientist at University College London, tells the publication. “It’s very hard to see how that’s going to be okay.”

The health information from the Inspiration4 astronauts sheds light on how space travel can affect private citizens who have not extensively trained for it. The findings also highlight changes to cells and DNA that can occur during short trips to space.

Biomarkers that changed during the Inspiration4 mission returned to normal a few months after the trip, suggesting that space travel doesn’t pose a greater risk to civilians than it does for trained astronauts, Christopher Mason , a geneticist at Cornell University who helped put together the atlas, says to New Scientist ’s Clare Wilson.

The Inspiration4 research also suggests women may recover faster from space travel than men. Data from the mission’s two male and two female participants, along with data from 64 NASA astronauts, indicated that gene activity related to the immune system was more disrupted in male astronauts, per the Guardian . And men’s immune systems took longer to return to normal once back on Earth.

Taken together, the new papers could help researchers learn how to ameliorate the harms space travel can cause, Afshin Beheshti , a co-author of the work and a researcher with the Blue Marble Space Institute of Science, says to the AP.

And the scientists say nothing in the data suggests humans should not go to space.

“There’s no showstopper,” Mason tells the Washington Post ’s Joel Achenbach. “There’s no reason we shouldn’t be able to safely get to Mars and back.”

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Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next .

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How the Lightning Can Best Use Their Cap Space

If any team is rejoicing over the recent news of an increased salary cap , it’s the Tampa Bay Lightning. Their championship run was handcuffed by a frozen salary cap during the COVID-19 pandemic, forcing them to break up the band sooner than they would have liked.

Imagine if the salary cap had jumped to $88 million after the 2020-21 season, the year the Lightning won their second-straight Stanley Cup . But alas, here we are. The cap is finally going up, and the team will have some breathing room for improvements – or at least to help maintain what they have. Here’s how the Lightning can best use their newfound cap space.

Re-Sign Steven Stamkos

We’re starting with the obvious. Extra cap space will help the Lightning hang on to their franchise player, Steven Stamkos .

Salary cap constraints contributed to this problem in the first place, and the Lightning should use this newfound space to lock down Stamkos as a Bolt for life. It would be worth it beyond just the on-ice product. That being said, keeping Stamkos would help the on-ice product. He scored 40 goals in 2023-24 and was one of the few players who produced in the playoffs.

Related: Lightning GM Confident Team Has Another Stanley Cup in Them

The salary cap should continue to rise, too, and his cap hit will be less of a factor. The Lightning’s franchise player could retire with the team while they keep their championship window open longer.

Lightning Need Defensive Help

Management already re-acquired Ryan McDonagh . Great start. The increased salary cap will allow them to take on that cap hit. However, if the Lightning play the cap game just right, they can add more depth. The defense needs all the help it can get. Early in the season, the team allowed more shots on goal than nearly every other team in the NHL.

The defense improved as players stepped up. However, they still allowed the 11th most goals this season – a dropoff from when they allowed the sixth-fewest goals just a couple of seasons ago. A team can never have too much defense, and they learned that they can’t rely on goaltender Andrei Vasilevskiy to save everyone.

Furthermore, after getting outmuscled by the Florida Panthers in the playoffs in a gentleman’s sweep , the Lightning need to prioritize their blue line. They had very few answers to stop the Panthers’ game plan and struggled to get past center ice. When they did, they didn’t have the defense to sustain anything, and the Panthers were quickly back on offense.

As the old saying goes, defense wins championships.

Now, for the sake of it, I’ll extend the meaning of more defensive help to include using the added cap space to keep top defensive stars like Victor Hedman . He’s going to be an unrestricted free agent after next season. Since the cap is expected to increase significantly again after next season, the Lightning have all the incentive to hammer out that deal and be done with it.

Lightning Need More High-Quality Depth Pieces On Offense

On the flip side, the Lightning could decide to focus on offense – beyond re-signing Stamkos. There are valid reasons for that, even if defense might be the area that needs the most help.

The Lightning offense didn’t have that much trouble scoring this season. But it was mostly through the sorcery of Hart Trophy finalist Nikita Kucherov . If Kucherov had a mediocre night, the Lightning, more often than not, did too. Having one player lift a team to the playoffs is not a sustainable model, and bolstering the offense would ease the pressure.

This isn’t to say their stars shouldn’t have to produce, but the Bolts wouldn’t have won the Cups they did if their offense had operated at this level in 2020 and 2021. That extra player, or two, who can score even just 20 to 25 goals, could do wonders.

The Lightning have big decisions to make this offseason. They have finally been given some breathing room. However, it’s up to them to decide what is the best route to win another Stanley Cup. Imagine a choose-your-own-adventure book, and you’re looking at the pages the Lightning can choose from. These options could have very different outcomes for the team that will impact what the roster will look like both as a contender and who represents them.

Scientists probe a space mystery: Why do people age faster during space travel?

Research finds bodies in space were stressed and showed dramatic signs of aging during the journey. but 95% of the indicators studied returned to normal within a few months..

Humanity's future may involve getting to a planet other than Earth ‒ but first people will have to survive the journey. That's why in a new series of papers scientists explore the impact of space travel on the human body from skin to kidneys to immune cells to genes.

Four civilian astronauts allowed themselves to be researched from top to bottom as they circled in low-Earth orbit for three days aboard the 2021 SpaceX Inspiration4 mission and then returned to their normal lives.

One of the most important observations was that although their bodies were stressed and showed dramatic signs of aging during the journey, 95% of the indicators studied returned to normal within a few months.

Radiation exposure apparently causes the acceleration of disease and damages cells "even in three to five days," Susan Bailey, a co-author on many of the studies and a radiation cancer biologist at Colorado State University in Fort Collins, said in a Monday video call with reporters.

Space news: Starship splashes down for first time in 4th test

Bailey and other scientists have studied astronauts before, most famously, identical twins Scott and Mark Kelly, during and after most of the 520 days Scott spent in space. ( Mark is now a senator from Arizona , choosing to run for political office after his wife, Congresswoman Gabby Giffords , now a gun control advocate , was shot in the head by a constituent.)

But this collection of studies, published Tuesday in Nature and related journals , shows the impact of space travel both on more people and also on a more diverse group, not just the exclusive people who can pass NASA's rigorous selection process.

Hayley Arceneaux , for instance, a physician assistant who served as the mission's medical director, was treated for cancer at age 10 and was one of the rare women in space. At 29, Arceneaux was also the youngest-ever space traveler.

Each of the four members of Inspiration4 represented a different decade of life, and began to provide the kind of diversity that will be crucial to understanding how space travel may impact people of different ages and health status and with different lived experiences, the researchers said.

"It really provides the foundation as we think ahead and more futuristically," Bailey said. The papers, she said, encouraged her and her peers to "think a little bit more about what it's really going to take for people to live in space for long periods of time, to thrive, to reproduce. How is all of that really going to happen?"

Bailey spent months studying the biology of the space travelers. But Monday's video conference was the first time she'd seen them face-to-face. "I'm familiar with your DNA," she told Arceneaux and fellow space traveler Chris Sembroski. "But it's nice to meet you."

Better understanding the damage that accumulates and how the body adapts to space travel will also lead researchers to treatments and fixes, said Bailey and the two other co-authors on the call, Christopher Mason, professor of genomics, physiology, and biophysics at Weill Cornell Medicine in New York, and Afshin Beheshti, an expert in bioinformatics at Blue Marble Space Institute of Science in Seattle.

In addition to age-related diseases, the papers revealed other problems space travelers can develop, like kidney stones. "Here we can treat that, but a kidney stone halfway to Mars, how are you going to treat that?" Beheshti wondered aloud. "That wasn't on the radar before" these papers.

"As we start to unravel some of this," Bailey added, "we'll improve not only our ability to deal with radiation exposure but also be addressing some of these age-related pathologies like cardiovascular disease that certainly could influence astronauts' performance en route to Mars."

Another insight: Women seem to recover faster from space damage than men, though Mason cautioned that more women need to be studied to better understand the effect and that faster recovery could come at the expense of higher long-term risk of breast and lung cancer from extended radiation exposure.

The lessons learned from space travelers could help folks on Earth, too, the researchers said.

Learning how to keep cells safe from radiation, for instance, might be transferable to help minimize damage to cancer patients undergoing radiation treatments, Mason said.

New protection measures could also be useful for people exposed to radiation at work or in case of a nuclear reactor disaster like the meltdown at the Fukushima Daiichi power plant in Japan after the 2011 earthquake there.

Because space travel speeds up aging, learning how to reverse or slow that process could help "extend health-span for us mere earthlings as well," Bailey said. The new skin study, for example, suggests approaches that might be used to help people keep their skin looking younger longer.

"There's all kinds of things that could potentially benefit people on Earth," she said.

The Inspiration4 mission, which raised $250 million for St. Jude Children's Research Hospital in Memphis , Tennessee, also relied on some experimental technologies for recording medical information, including a handheld ultrasound imaging device, smartwatch wearables, a measurement device to check for eye alignment and new methods for profiling the immune system as well as other cells and molecules.

These devices and approaches could be useful for Earth-bound settings that are far from major urban medical centers, Mason said.

Relying on civilians rather than NASA astronauts also made it easier to study the space travelers, who signed waivers and aren't subject to government regulations, he said. Their data will be made available to other researchers.

Both Arceneaux and Sembroski, a data engineer who works for the space technologies company Blue Origin, said they loved their spaceflight and would do it again in a second if given the chance. But they also hope many others are given the same opportunity.

"We're not going to see the civilization in space that we want without people being willing to share that experience," Sembroski said about sharing his data for research. "It was fun to be part of this."

"Our mission had, not only a lot of heart behind it," Arceneaux added, "but we really wanted to make a scientific impact."

Arceneaux said she doesn't mind the mark left by the biopsy used to study how her skin reacted to space travel. "I love my space scar!" she said.

"Better than a tattoo," Bailey responded.

The best news from the research on both Kelly and the Inspiration4 travelers, Mason said, is that there's "no show-stopper. There's no reason we shouldn't be able to get to Mars and back."

Radiation exposure probably means people shouldn't be taking multiple trips to and from the red planet, he said. But "so far, from all we've observed, the body is successfully adapting to the space environment."

Karen Weintraub can be reached at [email protected].