how can radio waves travel so far

Small Business Productivity, Tools and Tips – Android and iPhone Sync

What radio waves can travel through and what they cannot.

When Guglielmo Marconi began research into long-range radio in the late 19th century, the scientific community was skeptical. That he succeeded in transmitting radio signals more than 2000km met with much astonishment. What he had unwittingly done was discover the ionosphere, a layer in the atmosphere that is ionized to a degree by the sun’s ultraviolet rays. 

This affects radio waves and reflects them to earth, which bounces them upwards again. This repeated sequence enables us to transmit radio waves around the world. So, if radio waves can’t penetrate the ionosphere, what else will hinder them? Let’s look at what radio waves consist of, and then we’ll talk about their ability or otherwise to pass through certain materials.

Radio Waves Explained 

Developments in radio technology have brought us a long way in the past 100 years and more, but how do radio waves work? Before Marconi’s discovery, scientists believed that radio signals could only travel a straight line, as they were known to do in free space. Hence, there was a necessity for tall towers from which to transmit signals. A 100m high tower, for example, could send a signal up to around 30km, the limit set by the curvature of the earth. Marconi showed that radio waves could be bent and bounced by the ionosphere.

Radio waves form a small part of what is known as the electromagnetic spectrum (EMS). This consists not just of radio waves but also other forms of electromagnetic radiation such as gamma rays, microwaves, visible light, and more. Radio waves have among the longest wavelengths on the EMS. Imagine a rope held between two people. Move the rope up and down at one end, and a waveform moves across the rope.

This is what a radio wave would look like if we could see it. The wavelength is the distance between two ‘peaks’ in the wave. We also have to consider the frequency, which the number of waves that pass a given point in a set time. This is vital to understand so that different transmissions do not interfere with each other. 

Television signals are radio waves, but they are broadcast in a different frequency range to the radio.

What has this to do with the materials that radio waves can and cannot pass through? Let’s look more closely at this. 

What Can’t Radio Waves Pass-Through?

We’ve already seen that radio waves do not penetrate the ionosphere. We should explain that this refers to radio waves of up to 40MHz, the highest frequency bounced off the ionosphere. Why do radio waves bounce back?

As we mentioned, the ionosphere is partly ionized. 

This is because the UV light from the sun causes electrons to shake free from atoms, leaving a large proportion of free electrons hanging about in the ionosphere. When a radio wave hits the ionosphere, the energy created by the free electrons, as a result, causes the radio waves to be repelled or reflected. 

So, we know that radio waves up to 40MHz won’t pass through an ionized layer in the atmosphere. Remember that we explained the perceived limitations of radio transmissions before Marconi’s discovery. A line of sight was necessary, without obstructions, for successful transmission.

In some radio transmissions, interference can be caused by the waves being blocked by materials that they cannot penetrate. While radio waves can move through wood, bricks, and concrete to a certain extent, these materials can still cause interference. This is because radio waves meeting such objects can be reflected from buildings and other large structures, just like the ionosphere. This explains why the reception of radios and other radio frequency devices such as smartphones vary between locations.

For the record, as it covers a large bandwidth necessarily, television signals need to be above 40MHz so they cannot be bounced off the ionosphere, hence the tall towers in high locations used for TV transmissions. 

Radio waves will also be adversely affected by metal and water, which they cannot pass through. That is because water and metal are both electrical conductors. Like the ionosphere, metal and water contain many free electrons, which will vibrate when a radio wave hits the surface, and the wave will bounce back. 

To summarize, we now know that radio waves are affected by free electrons in electrical conductors such as metals and water and cannot pass through these materials. 

We have discovered that they can pass through non-conducting materials quite well but are losing propagation power with reflecting surfaces such as water, metal, and other materials. Furthermore, worldwide radio transmission is made possible by the radio waves being reflected by the ionosphere and the earth in a continuous sequence, allowing for transmissions to be made across great distances. 

Radio Waves

WHAT ARE RADIO WAVES?

Radio waves have the longest wavelengths in the electromagnetic spectrum. They range from the length of a football to larger than our planet. Heinrich Hertz proved the existence of radio waves in the late 1880s. He used a spark gap attached to an induction coil and a separate spark gap on a receiving antenna. When waves created by the sparks of the coil transmitter were picked up by the receiving antenna, sparks would jump its gap as well. Hertz showed in his experiments that these signals possessed all the properties of electromagnetic waves.

You can tune a radio to a specific wavelength—or frequency—and listen to your favorite music. The radio "receives" these electromagnetic radio waves and converts them to mechanical vibrations in the speaker to create the sound waves you can hear.

RADIO EMISSIONS IN THE SOLAR SYSTEM

Astronomical objects that have a changing magnetic field can produce radio waves. The radio astronomy instrument called WAVES on the WIND spacecraft recorded a day of bursts of radio waves from the Sun's corona and planets in our solar system.

Data pictured below show emissions from a variety of sources including radio bursts from the Sun, the Earth, and even from Jupiter's ionosphere whose wavelengths measure about fifteen meters in length. The far right of this graph shows radio bursts from the Sun caused by electrons that have been ejected into space during solar flares moving at 20% of the speed of light.

RADIO TELESCOPES

Radio telescopes look toward the heavens to view planets, comets, giant clouds of gas and dust, stars, and galaxies. By studying the radio waves originating from these sources, astronomers can learn about their composition, structure, and motion. Radio astronomy has the advantage that sunlight, clouds, and rain do not affect observations.

Since radio waves are longer than optical waves, radio telescopes are made differently than the telescopes used for visible light. Radio telescopes must be physically larger than an optical telescopes in order to make images of comparable resolution. But they can be made lighter with millions of small holes cut through the dish since the long radio waves are too big to "see" them. The Parkes radio telescope, which has a dish 64 meters wide, cannot yield an image any clearer than a small backyard optical telescope!

A VERY LARGE TELESCOPE

In order to make a clearer, or higher resolution, radio image, radio astronomers often combine several smaller telescopes, or receiving dishes, into an array. Together, these dishes can act as one large telescope whose resolution is set by the maximum size of the area. The National Radio Astronomy Observatory's Very Large Array (VLA) radio telescope in New Mexico is one of the world's premier astronomical radio observatories. The VLA consists of 27 antennas arranged in a huge "Y" pattern up to 36 km across (roughly one-and-one-half times the size of Washington, DC).

The techniques used in radio astronomy at long wavelengths can sometimes be applied at the shorter end of the radio spectrum—the microwave portion. The VLA image below captured 21-centimeter energy emissions around a black hole in the lower right and magnetic field lines pulling gas around in the upper left.

THE RADIO SKY

If we were to look at the sky with a radio telescope tuned to 408 MHz, the sky would appear radically different from what we see in visible light. Instead of seeing point-like stars, we would see distant pulsars, star-forming regions, and supernova remnants would dominate the night sky.

Radio telescopes can also detect quasars. The term quasar is short for quasi-stellar radio source. The name comes from the fact that the first quasars identified emit mostly radio energy and look much like stars. Quasars are very energetic, with some emitting 1,000 times as much energy as the entire Milky Way. However, most quasars are blocked from view in visible light by dust in their surrounding galaxies.

Astronomers identified the quasars with the help of radio data from the VLA radio telescope because many galaxies with quasars appear bright when viewed with radio telescopes. In the false-color image below, infrared data from the Spitzer space telescope is colored both blue and green, and radio data from the VLA telescope is shown in red. The quasar-bearing galaxy stands out in yellow because it emits both infrared and radio light.

Next: Microwaves

National Aeronautics and Space Administration, Science Mission Directorate. (2010). Radio Waves. Retrieved [insert date - e.g. August 10, 2016] , from NASA Science website: http://science.nasa.gov/ems/05_radiowaves

Science Mission Directorate. "Radio Waves" NASA Science . 2010. National Aeronautics and Space Administration. [insert date - e.g. 10 Aug. 2016] http://science.nasa.gov/ems/05_radiowaves

Discover More Topics From NASA

James Webb Space Telescope

Perseverance Rover

Parker Solar Probe

• Dogs Smell Cancer? – The Canine Nose Sniffs Out New Methods in Cancer Detection Technology
• Engineering Cinema: The Evolution of the Motion Picture Camera
• Shocking! – How Airplanes Defend Against Lightning
• How GPS Revolutionized Navigation
• Engineering a Masterpiece: The Science of Fresco Painting

USC Viterbi School of Engineering

Catch a Wave: Radio Waves and How They Work

About the Author: Andrew Schnickel

In Fall 2000, Andrew Schnickel was a Junior majoring in CECS who enjoyed running barefoot in the rain.

Introduction

You are driving down the open road, not a care in the world. It’s a sunny summer day and you have the car windows down. Everything seems almost perfect, yet something is missing. You turn on the radio, tune it to your favorite station (see Fig. 1), and instantly the car fills with sound. Suddenly, everything feels right. Radio is something most of us take for granted. Have you ever stopped to consider how a radio works? How does a radio know which station to play? What is AM, what is FM, and how are the two different? Why does FM sound better, but AM can be heard farther away? You have probably experienced a time when finding a particular radio station has been difficult. There are many factors involved in finding and receiving stations, factors such as modulation, broadcasting power, time of day, and geographical location. The key to getting the most out of your radio is to understand how radio works and how engineering has played a part in the development of a device which most of us use everyday.

Radio Basics

Am and fm differences.

Two characteristics, amplitude and frequency (see Fig. 2), mark the difference between AM and FM radio. AM stands for amplitude modulation, which means the amplitude of the radio signal is used to encode information. FM denotes frequency modulation, which uses a change in frequency to encode information. From this you can see that both AM and FM radio use modulation to encode information. “Modulation is the variation of some property of the radio carrier in a manner that conveys information” [1].

Modulation Explained

Amplitude modulation (am), frequency modulation (fm), sound quality and performance, signal strength, frequency range, interference, broadcast range.

• [1] J.J. Carr. “Elements of Electronic Communications.” Reston, Virginia: Reston Publishing Company, Inc., 1978.
• [2] R.S. Carson. “Radio Communications Concepts: Analog.” New York: John Wiley & Sons, 1990.
• [3] Editors and Engineers  The “Radio” Handbook.  Los Angeles: Editors and Engineers, 1942.
• ← Minerva: A Pioneer in Everyday Robots
• Fuel Injection →

Similar Posts

Chemical Engineering Your Dinner

Inside a Slot Machine

Engineering a Smooth Ride: Creating the Perfect Ski Through Shaping and Vibration Damping

Leave a reply cancel reply.

Your email address will not be published. Required fields are marked *

Advertisement

How are the Voyager spacecraft able to transmit radio messages so far?

• Share Content on Facebook
• Share Content on LinkedIn
• Share Content on Flipboard
• Share Content on Reddit
• Share Content via Email

The two Voyage spacecraft certainly have had an amazing track record. They were sent to photograph planets like Jupiter, Saturn and Neptune and have just kept on going past the outer edge of the solar system. Voyager 1 is currently over 7 billion miles (about 11 billion kilometers) away from Earth and is still transmitting -- it takes about 10 hours for the signal to travel from the spacecraft to Earth!

The Voyager spacecraft use 23-watt radios. This is higher than the 3 watts a typical cell phone uses, but in the grand scheme of things it is still a low-power transmitter. Big radio stations on Earth transmit at tens of thousands of watts and they still fade out fairly quickly.

The key to receiving the signals is therefore not the power of the radio, but a combination of three other things:

• Very large antenna dishes
• Directional antennas that point right at each other
• Radio frequencies without a lot of man-made interference on them

The antenna dishes that the Voyager spacecraft use are big. You may have seen people who have large satellite dishes in their yards. These are typically 2 or 3 meters (6 to 10 feet) in diameter. The Voyager spacecraft has an antenna dish that is 3.7 meters (14 feet) in diameter, and it transmits to a 34 meter (100 feet or so) dish on Earth. The Voyager dish and the Earth dish are pointed right at each other. When you compare your phone's stubby, little omni-directional antenna to a 34 meter directional antenna, you can see the main thing that makes a difference!

The Voyager satellites are also transmitting in the 8 GHz range , and there is not a lot of interference at this frequency. Therefore the antenna on Earth can use an extremely sensitive amplifier and still make sense of the faint signals it receives. Then when the Earth antenna transmits back to the spacecraft, it uses extremely high power (tens of thousands of watts) to make sure the spacecraft gets the message.

Frequently Asked Questions

What role do earth's ground stations play in receiving signals from distant spacecraft like voyager, how has technology advanced to maintain communication with voyager as it moves further away.

Please copy/paste the following text to properly cite this HowStuffWorks.com article:

• Become A Member
• Gift Membership
• Kids Membership
• Other Ways to Give
• Explore Worlds
• Defend Earth

How We Work

• Education & Public Outreach
• Space Policy & Advocacy
• Science & Technology
• Global Collaboration

Our Results

Learn how our members and community are changing the worlds.

Our citizen-funded spacecraft successfully demonstrated solar sailing for CubeSats.

Space Topics

• Planets & Other Worlds
• Space Missions
• Space Policy
• Planetary Radio
• Space Images

The Planetary Report

The exoplanet issue.

The expanding frontier of discovery.

Get Involved

Membership programs for explorers of all ages.

Get updates and weekly tools to learn, share, and advocate for space exploration.

Volunteer as a space advocate.

Support Our Mission

• Renew Membership
• Society Projects

The Planetary Fund

Accelerate progress in our three core enterprises — Explore Worlds, Find Life, and Defend Earth. You can support the entire fund, or designate a core enterprise of your choice.

• Strategic Framework
• News & Press

The Planetary Society

Know the cosmos and our place within it.

Our Mission

Empowering the world's citizens to advance space science and exploration.

• Explore Space
• Take Action
• Member Community
• Account Center
• “Exploration is in our nature.” - Carl Sagan

Emily Lakdawalla • Feb 24, 2012

This is how far human radio broadcasts have reached into the galaxy

The other day, I was playing around with stumbleupon and came across this photo, which -- well, it speaks for itself. Wow.

Gives you perspective, doesn't it? Actually, I'm a little surprised that the dot shows up on this image at all. Some people describe this as humbling, but for me, I see it as just the beginning. I'm very grateful to be a member of the very few generations of humanity that have ever lived who are (a) capable of creating radio broadcasts and (b) realizing how much more of the universe there is beyond what we've experienced.

I tweeted a link to it, and while I expected some retweets, I was surprised to see its spread -- I think it's probably the single most retweeted tweet I have ever written. There's probably several reasons for that. Links to photos are more likely to be retweeted than others. Very short but still substantial tweets are more likely to be retweeted, because it gives the repeater scope for their own commentary. And this is the sort of thing that can make just about anybody who is capable of operating a cell phone go "hmm," so it has wide appeal.

The one thing I feel bad about is that stumbleupon sent me directly to the photo on somebody else's website, and I didn't bother looking up its origin before I tweeted the link. So now I have, and I can tell you that the diagram was made by Adam Grossman on the jackadamblog , using an artist's concept of the Milky Way by Nick Risinger that he took from Wikipedia. They have a neato-looking iOS app, Dark Sky , that provides very short-term weather predictions. My apologies, Adam, for sending so much traffic directly to the photo rather than to your blog! Hopefully this post will correct that error.

A special note to the pedants: yes, I do realize that the signal from our radio and TV broadcasts is so attenuated by that 100-light-year boundary as to be undetectable except by some kind of magical alien technology. That's not the point. Don't be so literal!

One last thing: my apologies for no post yesterday and the likelihood of very few posts next week. I have a lot of other projects going right now that do not automatically produce blog posts, and not enough time.

The Time is Now.

As a Planetary Defender, you’re part of our mission to decrease the risk of Earth being hit by an asteroid or comet.

For full functionality of this site it is necessary to enable JavaScript. Here are instructions on how to enable JavaScript in your web browser .

• Skip to main content
• Keyboard shortcuts for audio player

Scientists have picked up a radio signal 'heartbeat' billions of light-years away

Ayana Archie

This image released by NASA on Tuesday, July 12, 2022, combined the capabilities of the James Webb Space Telescope's two cameras to create a never-before-seen view of a star-forming region in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), this combined image reveals previously invisible areas of star birth. NASA, ESA, CSA, STScI via AP hide caption

This image released by NASA on Tuesday, July 12, 2022, combined the capabilities of the James Webb Space Telescope's two cameras to create a never-before-seen view of a star-forming region in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), this combined image reveals previously invisible areas of star birth.

Astronomers at the Massachusetts Institute of Technology have picked up repetitive radio signals from a galaxy billions of light-years from Earth.

Scientists have not been able to pinpoint the exact location of the radio waves yet, but suspect the source could be neutron stars, which are made from collapsed cores of giant stars.

The signals have been occurring steadily and last up to three seconds, researchers say. Most fast radio bursts, or FRBs, only last a few milliseconds.

"Within this window, the team detected bursts of radio waves that repeat every 0.2 seconds in a clear periodic pattern, similar to a beating heart," MIT said in a statement .

On Dec. 21, 2019, researchers at the Dominion Radio Astrophysical Observatory in British Columbia, Canada, picked up a signal of a potential FRB, according to the MIT statement.

"Not only was it very long, lasting about three seconds, but there were periodic peaks that were remarkably precise, emitting every fraction of a second — boom, boom, boom — like a heartbeat," said Daniele Michilli, a postdoctoral researcher in the Massachusetts Institute of Technology's Kavli Institute for Astrophysics and Space Research. "This is the first time the signal itself is periodic."

Data on the bursts, including their frequency and how they change based on where the source is located in proximity to Earth could help researchers determine at what speed the universe is expanding.

The announcement about the repetitive radio signals follows the release earlier this week of the first images of the universe from the James Webb Space Telescope. Those images reveal some galaxies formed more than 13 billion years ago.

• Massachusetts Institute of Technology
• massachusetts institute

• The Magazine
• Stay Curious
• The Sciences
• Environment
• Planet Earth

Our Radio Signals Have Now Reached 75 Star Systems That Can See Us Too

We have been broadcasting for over 100 years. now a new 3d map of the galaxy reveals the stars these signals have reached that can also see earth..

When Guglielmo Marconi made the first “long-distance” radio broadcasts in 1895, his assistant tuned into from a less than a kilometer away. Marconi went on to develop the world’s first commercial radio system and, by the time of his death in 1937, radio signals were routinely used to communicate across the world.

These broadcasts have also travelled into space, signaling to all who care to tune in, that humanity has emerged as a technologically advanced species. The first signals have now been travelling for over hundred years, reaching distances that would have been unimaginable to Marconi.

That raises some interesting questions about the stars these signals have already reached. What kind of stars are they, do they host exoplanets and if so, are any potentially Earth-like and in the habitable zone? How many of these exoplanets might also be able to see us?

Now we get an answer thanks to the work of Lisa Kaltenegger at Cornell University in Ithaca and Jackie Faherty at the American Museum of Natural History in New York City. These astronomers have calculated the size of the sphere that our radio signals have covered since they left Earth, counted the stars that sit inside it and worked out which of them should also be able to see Earth transiting the Sun.

3D Star Map

All this is made possible by the Gaia Catalogue, a new 3D map of our galaxy showing the distance and motion of more than 100 million stars. The data comes from the European Space Agency’s Gaia spacecraft that was launched in 2013 and is mapping the position and motion of some 1 billion astronomical objects.

The resulting map is giving astronomers an entirely new way to study our galactic environment. Kaltenegger and Faherty’s project is a good example. Since Gaia measures how these stars are moving relative to one another, the researchers can work out for how long we have been visible to them and for how much longer.

Kaltenegger and Faherty say 75 stars systems that can see us, or soon will, sit within this 100 light year sphere. Astronomers have already observed exoplanets orbiting four of them.

These systems are generally well studied. The researchers say, for example, that the Ross128 star system is the 13th closest to the Sun and the second closest with a transiting Earth-size exoplanet. Then there is Teegarden’s Star, with at least two Earth-mass exoplanets and the Trappist-1 star system with seven Earth-sized planets, of which four are in the habitable zone.

Our signals continue to radiate away from us. So Kaltenegger and Faherty also pick out at the star systems set to receive our signals in the next 200 years or so and will also be able to see us. “1,715 stars within 326 light-years are in the right position to have spotted life on a transiting Earth since early human civilization, with an additional 319 stars entering this special vantage point in the next 5,000 years,” they say.

Rocky Exoplanets

Exoplanet statistics suggest that at least 25 per cent of these stars will have rocky exoplanets. So there should be at least 508 rocky planets in this population with a good view of earth. “Restricting the selection to the distance radio waves from Earth have traveled- about 100 light-years - leads to an estimated 29 potentially habitable worlds that could have seen Earth transit and also detect radio waves from our planet,” say Kaltenegger and Faherty.

Of course, the possibility of life on these worlds is entirely unknown. The next generation of space telescopes should allow astronomers to study these worlds in more detail, to determine their atmospheric make up and perhaps see continents and oceans.

To similarly equipped alien eyes, Earth will have long looked an interesting target. Life first emerged here some 4 billion years ago, ultimately giving our atmosphere its rich oxygen content and its other biomarkers, such as methane. If astronomers find similar conditions elsewhere, that will pique their interest.

It could even prompt searches for radio signals that may already be reaching us from these places. Marconi would surely have been amazed.

Ref: Past, Present And Future Stars That Can See Earth As A Transiting Exoplanet : arxiv.org/abs/2107.07936

Already a subscriber?

Register or Log In

Keep reading for as low as $1.99!

Sign up for our weekly science updates.

Save up to 40% off the cover price when you subscribe to Discover magazine.

Why Do Radio Signals Travel Farther at Night Than in the Day?

Not all radio waves travel farther at night than during the day, but some, short and medium wave, which AM radio signals fall under, definitely can given the right conditions. The main reason this is the case has to do with the signal interacting with a particular layer of the atmosphere known as the ionosphere, and how this interaction changes from the nighttime to the daytime.

The ionosphere is a layer of the upper atmosphere about 50 to 600 miles above sea level. It gets its name because it is ionized consistently by solar and cosmic radiation. In very simple terms, X-ray, ultraviolet, and shorter wavelengths of radiation given off by the Sun (and from other cosmic sources) release electrons in this layer of the atmosphere when these particular photons are absorbed by molecules. Because the density of molecules and atoms is quite low in the ionosphere (particularly in the upper layers), it allows free electrons to exist in this way for a short period of time before ultimately recombining. Lower in the atmosphere, where the density of molecules is greater, this recombination happens much faster.

What does this have to do with radio waves? Without interference, radio waves travel in a straight line from the broadcast source, ultimately hitting the ionosphere. What happens after is dependent on a variety of factors, notable among them being the frequency of the waves and the density of the free electrons. For AM waves, given the right conditions, they will essentially bounce back and forth between the ground and the ionosphere, propagating the signal farther and farther. So clearly the ionosphere can potentially play an important part in the terrestrial radio process. But it is the constantly shifting nature of the ionosphere that makes things really interesting. And for that, we’ll have to get a little more technical, though we’ll at the least spare you the math, and we’ll leave out a little of the complexity in an effort to not go full textbook on you.

In any event, the ionosphere’s composition changes most drastically at night, primarily because, of course, the Sun goes missing for a bit. Without as abundant a source of ionizing rays, the D and E levels (pictured right) of the ionosphere cease to be very ionized, but the F region (particularly F2) still remains quite ionized. Further, because the atmosphere is significantly less dense here then the E and D regions, it results in more free electrons (the density of which is key here).

When these electrons encounter a strong AM radio wave, they can potentially oscillate at the frequency of the wave, taking some of the energy from the radio wave in the process. With enough of them, as can happen in the F layer, (when the density of encountered electrons is sufficient relative to the specific signal frequency), and assuming they don’t just recombine with some ion (which is much more likely in the E and D layers in the daytime), this can very effectively refract the signal back down to Earth at sufficient strength to be picked up on your radio.

Depending on conditions, this process can potentially repeat several times with the signal bouncing down to the ground and back up. Thus, using this skywave, rather than just the normal daytime groundwave, AM radio signals can be propagated even thousands of miles.

Of course, this can become a major problem given that there are only a little over 100 allowed AM radio frequencies (restricted to keep signals interfering too much with one another), but around 5,000 AM radio stations in the United States alone. Given that at night, the signals from these stations can travel vast distances, this is just a recipe for stations interfering with one another. As a result, at night, AM stations in the United States typically reduce their power, go off the air completely until sunrise the next day, and/or possibly are required to use directional antennas, so their specific signal doesn’t interfere with other stations on the same frequency. On the other hand, FM stations don’t have to do any of this as the ionosphere doesn’t greatly affect their signals, which has the side benefit (or disadvantage, depending on your point of view) of severely limiting the range of the FM signals, which rely on groundwave propagation.

If you liked this article, you might also enjoy:

The “War of the Worlds” Mass Panic That Never Really Happened

When the U.S. Sent Several Hundred Million Needles Into Space (Project West Ford)

How One of the Most Beautiful Women in 1940s’ Hollywood Helped Make Certain Wireless Technologies Possible

The 72 Second Message from Outer Space

How the Gun on the Original Duck Hunt Game Worked

Bonus Fact:

AM Radio (Amplitude Modulation) was the first type of radio broadcasting used for mass-consumption by the public and is still widely used today. (Although AM radio is becoming less widespread in America, it is still the dominant type of terrestrial radio broadcasting in some countries, like Australia and Japan.) This type of signal works with the receiver translating and amplifying amplitude changes in a wave at a particular frequency into the sounds you hear coming from your speakers. FM Radio (Frequency Modulation), which started coming into its own in the 1950s, is broadcast in much the same way that AM is, but the receiver processes changes in the frequency of a wave, as opposed to the amplitude.

Dan Eder writes for the wildly popular interesting fact website TodayIFoundOut.com . To subscribe to Today I Found Out’s “Daily Knowledge” newsletter, click here or like them on Facebook here . You can also check ’em out on YouTube here .

This post has been republished with permission from TodayIFoundOut.com . Image by Kenji Yamamoto under Creative Commons license.

• Best Free VPN
• Best Cheap VPN
• NordVPN Review
• ExpressVPN Review
• ProtonVPN Review
• Surfshark Review
• Best Cloud Storage
• Best Web Hosting
• How to Tip Gizmodo

Galactic Map of Every Human Radio Broadcast Reveals How Isolated We Are

Those aliens better be nearby.

This map designed by Adam Grossman of The Dark Sky Company puts into perspective the enormity of these scales. The Milky Way stretches between 100,000 and 180,000 light-years across, depending on where you measure, which means a signal broadcast from one side of the galaxy would take 100,000 years or more to reach the other side. Now consider that our species started broadcasting radio signals into space only about a century ago. That's represented by a small blue bubble measuring 200 light-years in diameter surrounding the position of the Earth. For any alien civilizations to have heard us, they must be within the bubble.

The very first experimentation with electromagnetic radiation was conducted some 200 years ago, when Danish physicist and chemist Hans Christian Ørsted discovered that electric currents create magnetic fields. This research was expanded by scientists including Michael Faraday , and it eventually resulted in James Clerk Maxwell 's theory of electromagnetism outlined in 1865 and demonstrated by German physicist Heinrich Hertz's experiments more than two decades later. Even then, it wasn't until Italian inventor and electrical engineer Guglielmo Marconi developed long-range radio transmission technologies around the turn of the 20th century that our species really started broadcasting its existence out into the void.

.css-1i6271r{margin:0rem;font-size:1.625rem;line-height:1.2;font-family:UnitedSans,UnitedSans-roboto,UnitedSans-local,Helvetica,Arial,Sans-serif;padding:0.9rem 1rem 1rem;}@media(max-width: 48rem){.css-1i6271r{font-size:1.75rem;line-height:1;}}@media(min-width: 48rem){.css-1i6271r{font-size:1.875rem;line-height:1;}}@media(min-width: 64rem){.css-1i6271r{font-size:2.25rem;line-height:1;}}.css-1i6271r em,.css-1i6271r i{font-style:italic;font-family:inherit;}.css-1i6271r b,.css-1i6271r strong{font-family:inherit;font-weight:bold;} Even if you threw 100 darts, it's a near certainty that none would land in the little blue bubble of our radio waves

If we are optimistic, and we assume an advanced extraterrestrial species has the technological capabilities to detect humanity's very first radio waves (and distinguish them from the general background noise of the universe), we can estimate our farthest signals are a little more that 100 light-years away. If you threw a dart at the map of the Milky Way, and wherever that dart landed is where an advanced alien species resides, there would be a cosmically small probability that they live close enough to be aware of our existence. Even if you threw 100 darts, it's a near certainty that none would land in the little blue bubble of our radio waves.

The search for extraterrestrial intelligence (SETI) institute is constantly listening with our most capable radio telescopes , and they are broadcasting messages from us as well. But given the sheer size of the galaxy, SETI will likely have to listen and transmit for tens of thousands of years at least to have a chance of making contact with another intelligent species—and even that might not be long enough. Perhaps, in the meantime, we should contemplate Carl Sagan's next line in his Pale Blue Dot speech:

"In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves."

Source: Planetary Society

Jay Bennett is the associate editor of PopularMechanics.com. He has also written for Smithsonian, Popular Science and Outside Magazine. 

.css-cuqpxl:before{padding-right:0.3125rem;content:'//';display:inline;} Space .css-xtujxj:before{padding-left:0.3125rem;content:'//';display:inline;}

There are Lava Tubes on the Moon

Puffy Planets Are Prima Ballerinas

20 Facts You Didn’t Know About Apollo 11

Scientists Spots Rare ‘Missing Link’ Black Hole

Strange Eyeball Super-Earth May Be Habitable

This Is What Flicked on the Lights of the Universe

Scientists Spot the Milky Way’s ‘Exhaust Vent’

‘Stranded’ Astronauts Are Nothing New

Can Quantum Physics Explain This Cosmic Mystery?

SpaceX Will Make the ISS's Deorbiting Vehicle

3 New Super-Earths Just Dropped

Frontiers for Young Minds

• Download PDF

What Do Radio Waves Tell Us about the Universe?

Radio astronomy began in 1933 when an engineer named Karl Jansky accidentally discovered that radio waves come not just from inventions we create but also from natural stuff in space. Since then, astronomers have built better and better telescopes to find these cosmic radio waves and learn more about where they come from and what they can tell us about the universe. While scientists can learn a lot from the visible light they detect with regular telescopes, they can detect different objects and events – such as black holes, forming stars, planets in the process of being born, dying stars, and more – using radio telescopes. Together, telescopes that can see different kinds of waves – from radio waves to visible light waves to gamma rays – give a more complete picture of the universe than any one type of telescope can on its own.

When you look up at the night sky, you see the bright lights of stars. If you live in a dark place far from cities, you can see thousands of them. But the individual dots you see are all nearby stars. About 100 billion more stars, exist just in our galaxy, which is called the Milky Way. Beyond the Milky Way, astronomers think that about 100 billion more galaxies (each with their own 100 billion stars) exist. Almost all of these stars are invisible to your eyes, which cannot see the dim light from distant stars. Your eyes miss other things, too. The visible light that your eyes can see is only a tiny portion of what astronomers call the “ electromagnetic spectrum ,” the whole range of different light waves that exists. The electromagnetic spectrum also includes gamma rays, X-rays, ultraviolet radiation, infrared radiation, microwaves, and radio waves. Because human eyes can only see visible light, we have to build special telescopes to pick up the rest of that “spectrum” – and then turn them into pictures and graphs that we can see.

What is a Radio Wave?

Light is made up of tiny particles called “ photons .” Photons in visible light have a medium amount of energy. When photons have a little bit more energy, they become ultraviolet radiation, which you cannot see but which can give you a sunburn. With more energy than that, photons become X-rays, which travel right through you. If photons possess even more energy, they become gamma rays, which come out of stars when they explode.

But when photons have a little less energy than visible-light photons, they are known as infrared radiation. You can feel them as heat. Finally, we call the photons with the least energy “radio waves.” Radio waves come from strange spots in space – the coldest and oldest places and the stars with the most material stuffed into a small space. Radio waves tell us about parts of the universe we would not even know existed if we only used our eyes or telescopes that see visible photons.

Wavelength and Frequency

Radio astronomers use these radio photons to learn about the invisible universe. Photons travel in waves, like they are riding a roller coaster that just uses the same two pieces of track over and over [ 1 ]. The size of a photon’s wave – its wavelength – tells you about its energy. Figure 1 shows waves with two different wavelengths. If the wave is long, it does not have much energy; if it is short, it has a lot of energy. Radio waves do not have much energy, and that means they travel in big waves with long wavelengths. Radio waves can be hundreds of feet across or just a few centimeters across.

• Figure 1 - Photons travel in waves. The length of each wave is called a wavelength.

Astronomers also talk about how many of these waves pass a spot every second – the radio wave’s “ frequency .” You can think of frequency by imagining a pond of water. If you throw a rock into the water, ripples travel across the pond. If you stand in the water, the waves hit your ankles. The number of waves that smack into you in one second tells you the frequency of the waves. One wave per second is called 1 Hertz . A million waves per second is 1 MHz. If the waves are long, fewer of them hit you every second, so long waves have smaller frequencies. Radio waves have long wavelengths and small frequencies.

Radio Pioneers

The first radio astronomer did not mean to be the first radio astronomer. In 1933, a man named Karl Jansky was working on a project for Bell Laboratories, a lab in New Jersey named after Alexander Graham Bell, who invented the telephone. Engineers there were developing the first phone system that worked across the Atlantic Ocean. When people first tried making phone calls on that system, they heard a hissing sound in the background at certain times of the day. Bell Labs thought that noise was bad for business, so they sent Karl Jansky to find out what was causing it. He soon noticed that the hiss began when the middle of our galaxy rose in the sky and ended when it set (everything in the sky rises and sets just like the Sun and Moon do). He figured out that radio waves coming from the center of the galaxy were messing up the phone connection and causing the hiss. He – and the phone – had detected radio waves from space [ 1 ]. Jansky opened up a new, invisible universe. You can see a picture of the antenna used by Karl Jansky to detect radio waves from space in Figure 2 .

• Figure 2 - The founder of radio astronomy, Karl Jansky, stands with the antenna he built that detected the first radio waves identified as coming from space. Source: NRAO.

Inspired by Janksy’s research, a man named Grote Reber built a radio telescope in his backyard in Illinois. He finished the telescope, which was 31 ft across, in 1937 and used it to look at the whole sky and see where radio waves came from. Then, from the data he collected from his radio telescope, he made the first map of the “radio sky” [ 2 ].

Radio Telescope Talk

You can see visible light because the visible-light photons travel in small waves, and your eye is small. But because radio waves are big, your eye would need to be big to detect them. So while regular telescopes are a few inches or feet across, radio telescopes are much larger. The Green Bank Telescope in West Virginia is more than 300 ft wide and can be seen in Figure 3 . The Arecibo Telescope in the jungle in Puerto Rico is almost 1,000 ft across. They look like gigantic versions of satellite TV dishes, but they work like regular telescopes.

• Figure 3 - While instruments like the Green Bank Telescope, pictured here, may not look like traditional telescopes, they work much the same way but detect radio waves instead of visible light. They then turn those radio waves, which human eyes cannot see, into pictures and graphs that scientists can interpret. Source: NRAO.

To use a regular telescope, you point it at an object in space. Light from that object then hits a mirror or lens, which bounces that light to another mirror or lens, which then bounces the light again and sends it to your eye or a camera.

When an astronomer points a radio telescope at something in space, radio waves from space hit the telescope’s surface. The surface – which may be metal with holes in it, called mesh, or solid metal, like aluminum – acts like a mirror for radio waves. It bounces them up to a second “radio mirror,” which then bounces them into what astronomers call a “ receiver .” The receiver does what a camera does: it turns the radio waves into a picture. This picture shows how strong the radio waves are and where they are coming from in the sky.

Radio Vision

When astronomers look for radio waves, they see different objects and events than they see when they look for visible light. Places that seem dark to our eyes, or to regular telescopes, burn bright in radio waves. Places where stars form, for example, are full of dust. That dust blocks the light from getting to us, so the whole area looks like a black blob. But when astronomer turns radio telescopes to that spot, they can see straight through the dust: they can see a star being born.

Stars are born in giant clouds of gas in space. First, that gas clumps together. Then, because of gravity, more and more gas is attracted to the clump. The clump grows bigger and bigger and hotter and hotter. When it is huge and hot enough, it starts smashing hydrogen atoms, the smallest atoms that exist, together. When hydrogen atoms crash into each other, they make helium, a slightly bigger atom. Then, this clump of gas becomes an official star. Radio telescopes take pictures of these baby stars [ 3 ].

Radio telescopes show the secrets of the nearest star, too. The light we see from the Sun comes from near the surface, which is about 9,000oF. But above the surface, the temperature reaches 100,000oF. Radio telescopes help us learn more about these hot parts, which send out radio waves.

The planets in our solar system also have radio personalities. Radio telescopes show us the gases that swirl around Uranus and Neptune and how they move around. Jupiter’s north and south poles light up in radio waves. If we send radio waves toward Mercury, and then catch the radio waves that bounce back using a radio telescope, we can make a map almost as good as Google Earth [ 4 ].

When they look much farther away, radio telescopes show us some of the weirdest objects in the universe. Most galaxies have supermassive black holes in their centers. Black holes are objects that have a lot of mass squished into a tiny space. This mass gives them so much gravity that nothing, not even light, can escape their pull. These black holes swallow stars, gas, and anything else that comes too close. When that unlucky stuff feels the black hole’s gravity, it first spirals around the black hole. As it gets closer, it goes faster and faster. Huge jets, or columns, of electromagnetic radiation and matter that does not make it in to the black hole (sometimes taller than a whole galaxy is wide) form above and below the black hole. Radio telescopes show those jets in action ( Figure 4 ).

• Figure 4 - Galaxies that have supermassive black holes at their centers can shoot out jets of material and radiation, like those seen here, that are taller than the galaxy is wide. Source: NRAO.

Massive objects like these black holes warp the fabric of space, called space-time. Imagine setting a bowling ball, which weighs a lot, on a trampoline. The trampoline sags down. Weighty stuff in space makes space-time sag just like the trampoline. When radio waves coming from distant galaxies travel over that sag to get to Earth, the shape acts just like the shape of a magnifying glass on Earth: telescopes then see a bigger, brighter picture of the distant galaxy.

Radio telescopes also help solve one of the biggest mysteries in the universe: What is dark energy ? The universe is getting larger every second. And it gets larger faster and faster every second because “dark energy” is the opposite of gravity: Instead of pulling everything together, it pushes everything farther apart. But how strong is dark energy? Radio telescopes can help scientists to answer this question by looking at “ megamasers ” that occur naturally in some parts of space, a megamaser is kind of like a laser on Earth, but it sends out radio waves instead of the red or green light that we can see. Scientists can use megamasers to pin down the details of dark energy [ 5 ]. If scientists can figure out how far away those megamasers are, they can tell how far away different galaxies are, and then they can figure out how fast those galaxies are speeding away from us.

A Full Toolbox

If we only had telescopes that picked up visible light, we would be missing out on much of the action in the universe. Imagine if doctors had only a stethoscope as a tool. They could learn a lot about the patient’s heartbeat. But they could learn so much more if they also had an X-ray machine, a sonogram, an MRI instrument, and a CT scanner. With those tools, they could get a more complete picture of what was happening inside the patient’s body. Astronomers use radio telescopes together with ultraviolet, infrared, optical, X-ray, and gamma-ray telescopes for the same reason: to get a complete picture of what is happening in the universe.

Electromagnetic spectrum : ↑ The visible light that we can see is just a tiny part of the “electromagnetic spectrum.” Visible light is made of photons with medium energy. Photons with more energy are ultraviolet radiation, X-rays, and gamma rays (gamma rays have the most energy). Photons with less energy are infrared and radio waves (radio waves have the least energy).

Photon : ↑ Light is made of particles called photons, which travel in waves.

Wavelength : ↑ The size of the wave a photon travels in.

Frequency : ↑ The number of light waves that pass by a spot in one second.

Hertz : ↑ 1 Hz means that one wave passes by a spot in one second. One megahertz means one million waves pass by every second.

Receiver : ↑ The part of a radio telescope that takes the radio waves and turns them into a picture.

Dark energy : ↑ Dark energy acts like the opposite of gravity and pushes everything in the universe farther apart.

Megamaser : ↑ A natural laser in space that sends out radio waves, instead of red or green light like the kind that comes from a laser pointer.

[1] ↑ Jansky, K. G. 1993. Radio waves from outside the solar system. Nature 32, 66. doi: 10.1038/132066a0

[2] ↑ Reber, G. 1944. Cosmic static. Astrophys. J. 100, 297. doi: 10.1086/144668

[3] ↑ McKee, C. F., and Ostriker, E. 2007. Theory of star formation. Annu. Rev. Astron. Astrophys. 45, 565–687. doi: 10.1146/annurev.astro.45.051806.110602

[4] ↑ Ostro, S. J. 1993. Planetary radar astronomy. Rev. Mod. Phys. 65, 1235–79. doi: 10.1103/RevModPhys.65.1235

[5] ↑ Henkel, C., Braatz, J. A., Reid, M. J., Condon, J. J., Lo, K. Y., Impellizzeri, C. M. V., et al. 2012. Cosmology and the Hubble constant: on the megamaser cosmology project (MCP). IAU Symp. 287, 301. doi: 10.1017/S1743921312007223

Do you love all things radio and broadcasting? We are looking for writers!

Why Do AM Signals Travel Farther?

Site Owner & Radio Enthusiast

What would you say if you had to guess whether AM or FM signals could travel farther?

Although you might assume FM signals are more suited for long distances due to their prevalence, it’s actually AM. Why can AM signals travel far?

AM signals operate on a lower frequency, increasing the size of their wavelengths. Larger wavelengths can permeate solid objects more efficiently, allowing them to cross longer distances. The traveling distance of AM signals grows even more at night.

This article will answer all your questions on AM signal travel, so don’t miss it!

Table of Contents

Why Do AM Signals Travel Far?

As we established in the intro, AM radio waves can travel further than FM waves.

Now let’s explore the reasons why in more depth.

AM radio operates on a frequency range of 540 to 1700 kHz. FM radio uses frequencies between 88 and 108 MHz (at least in the United States; it can vary in other parts of the world).

As you can see, AM radio waves occur at a lower frequency between the two.

Low frequencies have bigger wavelengths, and high frequencies have shorter wavelengths.

That signal length is critical, allowing AM radio waves to pass through solid objects such as rocks, trees, hills, and buildings.

FM waves get stuck on these obstacles. The shorter wavelength prevents the radio wave from permeating through.

However, an FM radio wave’s ability to travel can be lengthened depending on where it’s broadcast from.

For example, the radio wave can travel further than usual in a wide open area because it’s unobstructed.

It will not outpace the distance an AM wave can travel.

How Far Can an AM Signal Reach?

Radio broadcasters and listeners must consider the distance AM and FM wavelengths can travel.

By day, an AM signal has an average broadcasting scope of 100 miles. By night, you can add on hundreds of miles more, says the FCC .

For comparison’s sake, an FM signal generally travels between 30 and 40 miles.

Do AM Signals Travel Farther by Day or By Night?

You’ll recall we mentioned a difference between an AM signal’s ability to travel at night versus by day. That’s no coincidence.

We just wrote a whole post dedicated to AM signal travel by night, so we’ll provide a brief recap here.

A radio wave’s ability to travel is affected by the ionosphere.

The ionosphere has molecules seeking bonds across several layers. The molecules will attach faster on some ionospheric levels than others.

During the day, the molecules remain unbonded more than at night. These unbonded molecules across the ionosphere operate the same as any obstacle.

An AM radio wave can pass through the obstacle, but it limits the extent of the signal.

This is why AM radio achieves an average broadcasting distance of 100 miles during the day.

The sun ionizes the molecules, so once it sets, they behave differently. The molecules will pair up at night, reducing their surface area and allowing AM waves to travel hundreds of miles.

The propensity for travel at that point is significant enough that the FCC requires some AM stations to reduce power or stop broadcasting at night if they don’t have safety measures.

Have you ever heard of such a measure required for FM radio? No!

You can usually tune into FM anytime, 24/7, because the signal distance doesn’t increase at night like an AM signal does.

Can You Extend the Distance of an AM Signal?

What if you want to extend AM signal range even more? You can try a few techniques, so let’s review them.

Reduce Interference

AM radio is even more prone to interference than FM, even if the former radio waves can pass through solid obstacles better.

As we discussed earlier, broadcasting in an open area is best.

The site should have few, if any, trees, hills, rocks, power lines, and buildings (well, besides the one you’re broadcasting from, if you’re indeed broadcasting indoors!).

Many everyday household objects can interfere with AM signals, dampening reception, as we wrote about here .

Be wary of anything electronic, from bug zappers to lights (even holiday lights), electric blankets, smartphone chargers, microwaves, computers and laptops, monitors, and televisions.

Consider powering off these devices when broadcasting or using AM radio.

If you’re listening to AM on a portable radio, you can also move the radio further from the source of these objects if you can’t unplug them for any reason.

Use at Night

AM radio waves travel much further at night.

Stations that you might have only barely been able to hear during the day because the interference was so severe can become clear and listenable once the sun sets.

However, we must stress that this only applies to some AM stations. Some will reduce their power load at night per FCC requirements.

When broadcasting at lower power, the distance the radio signals can travel might lessen.

Others have to stop broadcasting altogether!

Try an Antenna Booster

Positioning a portable radio antenna can improve the signal, but an antenna booster takes things one step further.

It amplifies the signal, enabling it to reach further distances.

You can always create an antenna booster or amplifier yourself or purchase one.

Here’s how an antenna booster works.

Most include an RF amplifier stage that can elevate the signal.

However, noise is equally amplified, so whether it’s a subtle hissing tone or a loud popping or humming, those sounds will come through loud and clear.

Make sure you know what’s causing interference around the AM radio signal, and do your best to minimize those sources of interference. This will spare everyone’s ears when they tune in.

Use a Transmitter

A radio transmitter is the last option to extend an AM signal’s length.

FM transmitters convert FM into AM signals, then transmit them over further distances, but you can also purchase an AM transmitter.

Transmitters can be high-level or low-level, the former of which uses high-level modulation.

That’s the standard choice when broadcasting on AM airwaves, especially if your transmitting power is mere kilowatts.

However, suppose you’re broadcasting but already have more transmitting power to your setup.

In that case, there’s no need to harness the power of high-level modulation. You can always use a low-power transmitter instead.

A radio transmitter includes a carrier oscillator, which produces a high-frequency carrier signal.

The carrier oscillator uses a sub-multiple frequency to keep the carrier frequency stable. This multiplies with a frequency multiplier to provide the required carrier frequency.

The transmitter also uses a buffer amplifier to isolate the frequency multiplier and carrier oscillator.

The amplifier sets the frequency multiplier’s input impedance and the carrier oscillator’s output impedance as the same.

Why do this? It prevents the multiplier from generating too large of a current.

There’s also a power amplifier. As the name suggests, this increases the carrier signal’s power.

Wrapping Up

AM signals can travel farther than FM signals due to the size of the wavelength.

The wavelengths are larger and thus have no issue passing through obstacles such as trees, buildings, and hills.

The traveling distance of AM signals amplifies even more at night.

Whereas the radio signal only travels about 100 miles during the day (which is still over 50 miles more than an FM radio wave’s average traveling distance), it becomes hundreds of miles more after dark due to sky wave propagation.

While you can use handy tools like a radio transmitter or antenna booster to lengthen an AM signal, remember that noise is often amplified with the signal.

Reducing noise as much as possible will enhance the clarity of the signal.

When my grandfather would come to visit me as a kid, we used to sit in his RV and listen to the activity on his CB radio. His nickname for me was “Charlie” and asked me what my call sign would be. I told him it’s “Wide Receiver”, as a play on receiving radio signals and also for my dream of playing a wide receiver in football at the time.

Similar Posts

Antennas vs. Aerials: Is There a Difference for Radios?

Is there a difference between antennas and aerials? We’ll explore ahead!

Roberts Chronoplus2 review

William Baker Contributing Editor A bedside clock radio is one of the most important tools that…

How to Listen to AM Radio On Your Phone (iPhone + Android)

You can listen to AM radio on today’s smartphones, whether you own an Android or iPhone. Tune in to learn how!

What’s the Difference Between Ham Radio VS CB Radio VS Walkie Talkie

How are walkie-talkies, CB radios, and ham radios different? This guide will tell you what you need to know.

Pure Pop Maxi review

William Baker Contributing Editor These days, if you want expansive stereo sound in your home, you’ll…

Roberts Rambler BT review

William Baker Contributing Editor Do you love all things retro? Are you addicted to the warm…

• Subscribe to BBC Science Focus Magazine
• Previous Issues
• Future tech
• Everyday science
• Planet Earth
• Newsletters

© Getty Images

How far from Earth could aliens detect our radio signals?

Asked by: Anna Briggs, Plymouth

Robert Matthews

While commercial radio broadcasts began around 100 years ago, these early transmissions used frequencies that were either mopped up by the atmosphere or drowned out by radio emission from the Sun.

In contrast, military radar transmissions set up during the Cold War to detect incoming ballistic missiles have the power and frequency characteristics to be detected over hundreds of light-years – and have already broadcast our existence to any aliens within around 60 light-years of the Earth.

• The thought experiment: What would happen if aliens contacted us?
• How could we talk fluently to aliens?
• How far do we travel through space every day?
• Could we ever detect other universes?

Subscribe to BBC Science Focus Magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun facts.

Share this article

• Terms & Conditions
• Privacy policy
• Cookies policy
• Code of conduct
• Magazine subscriptions
• Manage preferences

Advertisement

Photo Appears to Capture Path of Bullet Used in Assassination Attempt

Michael Harrigan, a retired F.B.I. special agent, said the image captured by Doug Mills, a New York Times photographer, seems to show a bullet streaking past former President Donald J. Trump.

• Share full article

By John Ismay

Reporting from Washington

• Published July 14, 2024 Updated July 15, 2024

Follow the latest news on the Trump assassination attempt .

In documenting the Pennsylvania campaign rally on Saturday afternoon that turned into an attempt on a former president’s life, Doug Mills, a veteran New York Times photographer, appeared to capture the image of a bullet streaking past former President Donald J. Trump’s head.

That is the assessment of Michael Harrigan, a retired F.B.I. special agent who spent 22 years in the bureau.

“It absolutely could be showing the displacement of air due to a projectile,” Mr. Harrigan said in an interview on Saturday night after reviewing the high-resolution images that Mr. Mills filed from the rally. “The angle seems a bit low to have passed through his ear, but not impossible if the gunman fired multiple rounds.”

Simple ballistic math showed that capturing a bullet as Mr. Mills likely did in a photo was possible, Mr. Harrigan said.

Mr. Mills was using a Sony digital camera capable of capturing images at up to 30 frames per second. He took these photos with a shutter speed of 1/8,000th of a second — extremely fast by industry standards.

The other factor is the speed of the bullet from the firearm. On Saturday law enforcement authorities recovered an AR-15-type semiautomatic rifle at the scene from a deceased white man they believe was the gunman.

“If the gunman was firing an AR-15-style rifle, the .223-caliber or 5.56-millimeter bullets they use travel at roughly 3,200 feet per second when they leave the weapon’s muzzle,’’ Mr. Harrigan said. “And with a 1/8,000th of a second shutter speed, this would allow the bullet to travel approximately four-tenths of a foot while the shutter is open.”

“Most cameras used to capture images of bullets in flight are using extremely high speed specialty cameras not normally utilized for regular photography, so catching a bullet on a side trajectory as seen in that photo would be a one in a million shot and nearly impossible to catch even if one knew the bullet was coming,” he said.

In Mr. Harrigan’s last assignment, he led the bureau’s firearms training unit and currently works as a consultant in the firearms industry.

“Given the circumstances, if that’s not showing the bullet’s path through the air, I don’t know what else it would be,” he said.

John Ismay is a reporter covering the Pentagon for The Times. He served as an explosive ordnance disposal officer in the U.S. Navy. More about John Ismay

Our Coverage of the Trump Rally Shooting

The Investigation : F.B.I. officials told Congress that the 20-year-old gunman who tried to kill Donald Trump used his cellphone and other devices to search for images of Trump and President Biden .

Security Blind Spots : Even as investigators continue to examine what happened at the Trump rally, it is already clear that there were multiple missed opportunities to stop the gunman  before the situation turned deadly.

The Gunman : In interviews, former classmates of the suspect described him as intelligent but solitary , someone who tried to avoid teasing by fellow students.

Secret Service Director : Kimberly Cheatle  returned in 2022 to lead the agency she had served for nearly 30 years. Now, the assassination attempt on Trump has thrown her tenure into uncertainty .

Fears of What’s Next : Among voters, there is growing anxiety that America’s political divide is nearly beyond repair, and the shooting only made things worse .

What we know about CrowdStrike’s update fail that’s causing global outages and travel chaos

A faulty software update issued by security giant CrowdStrike has resulted in a massive overnight outage that’s affected Windows computers around the world , disrupting businesses, airports, train stations, banks, broadcasters and the healthcare sector.

CrowdStrike said the outage was not caused by a cyberattack, but was the result of a “defect” in a software update for its flagship security product, Falcon Sensor. The defect caused any Windows computers that Falcon is installed on to crash without fully loading.

“The issue has been identified, isolated and a fix has been deployed,” said CrowdStrike in a statement on Friday . Some businesses and organizations are beginning to recover, but many expect the outages to drag on into the weekend or next week given the complexity of the fix. CrowdStrike CEO George Kurtz told NBC News that it may take “some time for some systems that just automatically won’t recover.” In a later tweet , Kurtz apologized for the disruption.

Here’s everything you need to know about the outages.

What happened?

Late Thursday into Friday, reports began to emerge of IT problems wherein Windows computers were getting stuck with the infamous “blue screen of death” — a bright blue error screen with a message that displays when Windows encounters a critical failure, crashes or cannot load.

The outages were first noticed in Australia early on Friday, and reports quickly came in from the rest of Asia and Europe as the regions began their day, as well as the United States.

Within a short time, CrowdStrike confirmed that a software update for Falcon had malfunctioned and was causing Windows computers that had the software installed to crash. Falcon lets CrowdStrike remotely analyze and check for malicious threats and malware on installed computers.

At around the same time, Microsoft reported a significant outage at one of its most used Azure cloud regions covering much of the central United States. A spokesperson for Microsoft told TechCrunch that its outage was unrelated to CrowdStrike’s incident .

Around Friday noon (Eastern time), Microsoft CEO Satya Nadella posted on X saying the company is aware of the CrowdStrike botched update and is “working closely with CrowdStrike and across the industry to provide customers technical guidance and support to safely bring their systems back online.”

What is CrowdStrike and what does Falcon Sensor do?

CrowdStrike, founded in 2011, has quickly grown into a cybersecurity giant. Today the company provides software and services to 29,000 corporate customers, including around half of Fortune 500 companies, 43 out of 50 U.S. states and eight out of the top 10 tech firms, according to its website .

The company’s cybersecurity software, Falcon, is used by enterprises to manage security on millions of computers around the world. These businesses include large corporations, hospitals, transportation hubs and government departments. Most consumer devices do not run Falcon and are unaffected by this outage.

One of the company’s biggest recent claims to fame was when it caught a group of Russian government hackers breaking into the Democratic National Committee ahead of the 2016 U.S. presidential election. CrowdStrike is also known for using memorable animal-themed names for the hacking groups it tracks based on their nationality, such as: Fancy Bear , believed to be part of Russia’s General Staff Main Intelligence Directorate, or GRU; Cozy Bear , believed to be part of Russia’s Foreign Intelligence Service, or SVR; Gothic Panda , believed to be a Chinese government group; and Charming Kitten , believed to be an Iranian state-backed group. The company even makes action figures to represent these groups, which it sells as swag .

CrowdStrike is so big it’s one of the sponsors of the Mercedes F1 team , and this year even aired a Super Bowl ad — a first for a cybersecurity company. 

Who are the outages affecting?

Practically anyone who during their everyday life interacts with a computer system running software from CrowdStrike is affected, even if the computer isn’t theirs. 

These devices include the cash registers at grocery stores, departure boards at airports and train stations, school computers, your work-issued laptops and desktops, airport check-in systems, airlines’ own ticketing and scheduling platforms, healthcare networks and many more. Because CrowdStrike’s software is so ubiquitous, the outages are causing chaos around the world in a variety of ways. A single affected Windows computer in a fleet of systems could be enough to disrupt the network. 

TechCrunch reporters around the world are seeing and experiencing outages, including at points of travel, doctors’ offices and online. Early on Friday, the Federal Aviation Administration put in effect a ground stop, effectively grounding flights across the United States, citing the disruption. It looks like so far the national Amtrak rail network is functioning as normal. 

What is the U.S. government doing so far?

Given that the problem stems from a company, there isn’t much that the U.S. federal government can do. According to a pool report, President Biden was briefed on the CrowdStrike outage, and “his team is in touch with CrowdStrike and impacted entities.” That’s in large part because the federal government is a customer of CrowdStrike and also affected.

Several federal agencies are affected by the incident, including the Department of Education , and Social Security Administration, which said Friday that it closed its offices as a result of the outage.

The pool report said Biden’s team is “engaged across the interagency to get sector by sector updates throughout the day and is standing by to provide assistance as needed.” 

In a separate tweet, Homeland Security said it was working with its U.S. cybersecurity agency CISA, CrowdStrike and Microsoft — as well as its federal, state, local and critical infrastructure partners — to “fully assess and address system outages.”

There will no doubt be questions for CrowdStrike (and to some extent Microsoft, whose unrelated outage also caused disruption overnight for its customers) from government and congressional investigators. 

For now, the immediate focus will be on the recovery of affected systems.

How do affected customers fix their Windows computers?

The major problem here is that CrowdStrike’s Falcon Sensor software malfunctioned, causing Windows machines to crash, and there’s no easy way to fix that. 

So far, CrowdStrike has issued a patch, and it has also detailed a workaround that could help affected systems function normally until it has a permanent solution. One option is for users to “reboot the [affected computer] to give it an opportunity to download the reverted channel file,” referring to the fixed file.

In a message to users , CrowdStrike detailed a few steps customers can take, one of which requires physical access to an affected system to remove the defective file. CrowdStrike says users should boot the computer into Safe Mode or Windows Recovery Environment, navigate to the CrowdStrike directory, and delete the faulty file “C-00000291*.sys.”

The wider problem with having to fix the file manually could be a major headache for companies and organizations with large numbers of computers, or Windows-powered servers in datacenters or locations that might be in another region, or an entirely different country.

CISA warns that malicious actors are ‘taking advantage’ of the outage

In a statement on Friday, CISA attributed the outages to the faulty CrowdStrike update and that the issue was not due to a cyberattack. CISA said that it was “working closely with CrowdStrike and federal, state, local, tribal and territorial partners, as well as critical infrastructure and international partners to assess impacts and support remediation efforts.”

CISA did note, however, that it has “observed threat actors taking advantage of this incident for phishing and other malicious activity.” The cybersecurity agency did not provide more specifics, but warned organizations to stay vigilant.

Malicious actors can and will exploit confusion and chaos to carry out cyberattacks on their own. Rachel Tobac, a social engineering expert and founder of cybersecurity firm SocialProof Security, said in a series of posts on X to “verify people are who they say they are before taking sensitive actions.”

“Criminals will attempt to use this IT outage to pretend to be IT to you or you to IT to steal access, passwords, codes, etc.,” Tobac said.

What do we know about misinformation so far?

It’s easy to understand why some might have thought that this outage was a cyberattack. Sudden outages, blue screens at airports, office computers filled with error messages, and chaos and confusion. As you might expect, a fair amount of misinformation is already flying around , even as social media sites incorrectly flag trending topics like “cyberattack.”

Remember to check official sources of news and information, and if something seems too good to be true, it might just well be.

TechCrunch will keep this report updated throughout the day.

TechCrunch’s Ram Iyer contributed reporting.

More TechCrunch

Get the industry’s biggest tech news, techcrunch daily news.

Every weekday and Sunday, you can get the best of TechCrunch’s coverage.

Startups Weekly

Startups are the core of TechCrunch, so get our best coverage delivered weekly.

TechCrunch Fintech

The latest Fintech news and analysis, delivered every Tuesday.

TechCrunch Mobility

TechCrunch Mobility is your destination for transportation news and insight.

GM’s Cruise abandons Origin robotaxi, takes $583 million charge

GM’s self-driving car subsidiary Cruise is scrapping plans to build the Origin  — a purpose-built robotaxi with no steering wheel or pedals — and will instead use the next-generation Chevrolet…

Hackers shut down heating in Ukrainian city with malware, researchers say

Cybersecurity firm Dragos and Ukrainian authorities found a cyberattack targeting critical infrastructure in Lviv.

Telegram’s userbase climbs to 950M, plans to launch app store

Messaging app Telegram has reached 950M active users, and it aims to cross the 1 billion mark this year, founder Pavel Durov said.

India scraps ‘angel tax’ in boost for startups

India’s federal government has removed the so-called “angel tax” for all classes of investors, delivering a major victory to the country’s startup ecosystem that had lobbied for years against the…

Kakao founder issued arrest warrant by Seoul court

A Seoul court issued an arrest warrant for Brian Kim, the founder of South Korean internet giant Kakao, on allegations of stock price manipulation related to the company’s takeover of…

Wiz walks away from Google’s $23B acquisition offer: Read the CEO’s note to employees

Cybersecurity startup Wiz has turned down a $23 billion acquisition offer from Alphabet, Google’s parent company, according to a source familiar with discussions. Despite the offer representing a substantial premium…

Monarch Tractor CEO says $133M raise will help it escape ‘quite a challenging time’

Monarch Tractor was in a tricky spot late last year as the autonomous electric tractor startup juggled growth and an uncertain fundraising environment. Now, with $133 million in new funds,…

TechCrunch Space: SpaceX’s big plans to bring the ISS back to Earth

Hello and welcome back to TechCrunch Space. Before we begin, a quick note: I write this newsletter on Friday and it gets delivered to you on Monday. So if I…

17-year-old Eric Zhu’s startup was built in a high school bathroom — now it’s raised $2.3M and is emerging from stealth

Eric Zhu started building Aviato, an analytical platform for private market data, in a very atypical place for an entrepreneur: the bathroom in his Carmel, Indiana, high school. Now the 17-year-old’s…

The Scene’s new app helps New Yorkers find dining and nightlife spots

Choosing between New York City’s nearly 25,000 restaurants can be overwhelming. The pressure is especially high when you’re trying to impress a first date (or investor) or entertain family from…

Google’s Jigsaw open sources Altitude to help online platforms weed out extremist content

Nine months on, and Jigsaw is now formally handing Altitude over to Tech Against Terrorism, which will continue its development and maintenance.

Be a TechCrunch Disrupt 2024 volunteer

TechCrunch Disrupt 2024 in San Francisco is fast approaching, and we’re seeking highly motivated volunteers to support our events team. If you dream of becoming a startup founder, marketer, or…

Cohere raises $500M to beat back generative AI rivals

Unlike OpenAI, Anthropic, Mistral and many of its generative AI startup rivals, Cohere doesn’t have a big consumer focus.

Swiggy turns Minis into a link-in-bio platform

Indian food delivery and quick commerce startup Swiggy is pivoting one of its smaller businesses, Swiggy Minis, into a link-in-bio service.

Fintech Fragment eases ledger problems, nabs $9M from Stripe, Jack Altman, BoxGroup, others

Fragment’s digital ledger API applies real-time, double entry accounting to find where things aren’t adding up.

Linx emerges from stealth with $33M to lock down the new security perimeter: Identity

Identity management is one of the most common fulcrums around which security breaches have pivoted in the last several years. One of the main reasons it has become the gift…

Featured Article

Pesa unlocks new markets to keep remittances flowing to emerging economies

Founders of Pesa, a remittance fintech, know too well how costly, inaccessible and unreliable remittance services drive people to opt for risky informal channels —  like WhatsApp groups  — to transfer money.  Their firsthand experience using informal channels and realizing how prevalent their use was among Africans living in the…

The Asus ROG Ally X turns PC gaming into a portable console

A little more than a year after launching the ROG Ally, Asus is releasing a refined version of its portable device, the ROG Ally X. This Windows-based machine starts shipping…

CIA AI director Lakshmi Raman claims the agency is taking a ‘thoughtful approach’ to AI

As a part of TechCrunch’s ongoing Women in AI series, which seeks to give AI-focused women academics and others their well-deserved — and overdue — time in the spotlight, TechCrunch interviewed Lakshmi…

What Kamala Harris has said about AI, tech regulation and more

With President Joe Biden dropping out of the race, Vice President Kamala Harris may become the Democrats’ new nominee. In announcing his plans, Biden offered his “full support and endorsement…

Joe Biden drops out of presidential race

U.S. President Joe Biden has announced he no longer plans to seek reelection, a decision that follows weeks of growing pressure from some Democratic Party supporters, including high-profile tech investors…

Made by Google 2024: Pixel 9, Gemini, a new foldable and other things to expect from the event

Google is expected to announce four Pixel devices: the Pixel 9, Pixel 9 Pro, Pixel 9 Pro XL and Pixel 9 Pro Premium, running Android 15.

WazirX halts trading after $230 million ‘force majeure’ loss

WazirX, one of India’s largest cryptocurrency exchanges, has “temporarily” suspended all trading activities on its platform days after losing about $230 million, nearly half of its reserves, in a security…

From Yandex’s ashes comes Nebius, a ‘startup’ with plans to be a European AI compute leader

Subject to shareholder approval, Yandex N.V. is adopting the name of one of its few remaining assets, an AI cloud platform called Nebius AI which it birthed last year.

Bethesda Game Studios employees form a ‘wall-to-wall’ union

Employees at Bethesda Game Studios — the Microsoft-owned game developer that produces the Elder Scrolls and Fallout franchises — are joining the Communications Workers of America union. Quality assurance testers…

CrowdStrike’s update fail causes global outages and travel chaos

This week saw one of the most widespread IT disruptions in recent years linked to a faulty software update from popular cybersecurity firm CrowdStrike. Businesses across the world reported IT…

Unpacking how Alphabet’s rumored Wiz acquisition could affect VC

Alphabet, the parent company of Google, is in advanced talks to acquire cybersecurity startup Wiz for $23 billion, the Wall Street Journal reported on Sunday. TechCrunch’s sources heard similar and…

Microsoft says 8.5M Windows devices were affected by CrowdStrike outage

Around 8.5 million devices — less than 1 percent of Windows machines globally — were affected by the recent CrowdStrike outage, according to a Microsoft blog post by David Weston,…

Some Black startup founders feel betrayed by Ben Horowitz’s support for Trump

Trump is an advocate for a number of policies that could be harmful to people of color.

Strava’s next chapter: New CEO talks AI, inclusivity, and why ‘dark mode’ took so long

TechCrunch sat down with Strava’s new CEO in London for a wide-ranging interview, delving into what the company is prioritizing, and what we can expect in the future as the company embarks on its “next chapter.”