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Is there any sound in space? An astronomer explains

How far can sound travel through space, since it’s so empty? Is there an echo in space? – Jasmine, age 14, Everson, Washington

In space, no one can hear you scream.

You may have heard this saying. It’s the tagline from the famous 1979 science fiction movie “ Alien .” It’s a scary thought, but is it true? The simple answer is yes, no one can hear you scream in space because there is no sound or echo in space.

I’m a  professor of astronomy , which means I study space and how it works. Space is silent – for the most part.

How sound works

To understand why there’s no sound in space, first consider how sound works.  Sound is a wave  of energy that moves through a solid, a liquid or a gas.

Sound is  a compression wave . The energy created when your vocal cords vibrate slightly compresses the air in your throat, and the compressed energy travels outward.

A good analogy for sound is a  Slinky toy . If you stretch out a Slinky and push hard on one end, a  compression wave travels  down the Slinky.

When you talk, your vocal cords vibrate. They jostle air molecules in your throat above your vocal cords, which in turn jostle or bump into their neighbors, causing a sound to come out of your mouth.

Sound moves through air the same way it moves through your throat. Air molecules near your mouth bump into their neighbors, which in turn bump into their neighbors, and the sound moves through the air. The  sound wave travels quickly , about 760 miles per hour (1,223 kilometers per hour), which is faster than a commercial jet.

Space is a vacuum

So what about in space?

Space is a vacuum, which means it contains almost no matter. The word vacuum  comes from the Latin word for empty .

Sound is carried by atoms and molecules. In space, with no atoms or molecules to carry a sound wave, there’s no sound. There’s nothing to get in sound’s way out in space, but there’s nothing to carry it, so it doesn’t travel at all. No sound also means no echo.  An echo  happens when a sound wave hits a hard, flat surface and bounces back in the direction it came from.

By the way, if you were caught in space outside your spacecraft with no spacesuit, the fact that no one could hear your cry for help is the least of your problems. Any air you still had in your lungs would expand because it was at higher pressure than the vacuum outside. Your lungs would rupture. In a mere  10 to 15 seconds , you’d be unconscious due to a lack of oxygen.

Sound in the solar system

Scientists have wondered how human voices would sound on our nearest neighboring planets, Venus and Mars. This experiment is hypothetical because  Mars is usually below freezing , and its atmosphere is  thin, unbreathable carbon dioxide .  Venus is even worse  – its air is hot enough to melt lead, with a thick carbon dioxide atmosphere.

On Mars, your voice would sound tinny and hollow, like the  sound of a piccolo .  On Venus , the pitch of your voice would be much deeper, like the sound of a booming bass guitar. The reason is the thickness of the atmosphere. On Mars the thin air creates a high-pitched sound, and on Venus the thick air creates a low-pitched sound. The team that worked this out  simulated other solar system sounds , like a waterfall on Saturn’s moon Titan.

Deep space sounds

While space is a good enough vacuum that normal sound can’t travel through it, it’s actually not a perfect vacuum, and it does have some particles floating through it.

Beyond the Earth  and its atmosphere, there are five particles in a typical cubic centimeter – the volume of a sugar cube – that are mostly hydrogen atoms. By contrast, the air you are breathing is 10 billion billion (10 19)  times more dense. The density goes down with distance from the Sun, and in  the space between stars  there are 0.1 particles per cubic centimeter. In vast  voids between galaxies , it is a million times lower still – fantastically empty.

The voids of space are kept very hot by radiation from stars. The very spread-out matter found there is in a physical state  called a plasma .

A plasma is a gas in which electrons are separated from protons. In a plasma, the  physics of sound waves get complicated . Waves travel much faster in this low-density medium, and their wavelength is much longer.

In 2022, NASA released a  spectacular example of sound in space . It used X-ray data to make an audible recording that represents the way a massive black hole stirs up plasma in the Perseus galaxy cluster, 250 million light years from Earth. The black hole itself emits no sound, but the diffuse plasma around it carries very long wavelength sound waves.

The natural sound is far too low a frequency for the human ear to hear, 57 octaves below middle C, which is the middle note on a piano and in the middle of the range of sound people can hear. But after raising the frequency to the audible range, the result is chilling – it’s the sound of a black hole growling in deep space.

This article was first published on The Conversation .

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Propagation of an Electromagnetic Wave

Electromagnetic waves are waves which can travel through the vacuum of outer space. Mechanical waves, unlike electromagnetic waves, require the presence of a material medium in order to transport their energy from one location to another. Sound waves are examples of mechanical waves while light waves are examples of electromagnetic waves.

Electromagnetic waves are created by the vibration of an electric charge. This vibration creates a wave which has both an electric and a magnetic component. An electromagnetic wave transports its energy through a vacuum at a speed of 3.00 x 10 8 m/s (a speed value commonly represented by the symbol c ). The propagation of an electromagnetic wave through a material medium occurs at a net speed which is less than 3.00 x 10 8 m/s. This is depicted in the animation below.

The mechanism of energy transport through a medium involves the absorption and reemission of the wave energy by the atoms of the material. When an electromagnetic wave impinges upon the atoms of a material, the energy of that wave is absorbed. The absorption of energy causes the electrons within the atoms to undergo vibrations. After a short period of vibrational motion, the vibrating electrons create a new electromagnetic wave with the same frequency as the first electromagnetic wave. While these vibrations occur for only a very short time, they delay the motion of the wave through the medium. Once the energy of the electromagnetic wave is reemitted by an atom, it travels through a small region of space between atoms. Once it reaches the next atom, the electromagnetic wave is absorbed, transformed into electron vibrations and then reemitted as an electromagnetic wave. While the electromagnetic wave will travel at a speed of c (3 x 10 8 m/s) through the vacuum of interatomic space, the absorption and reemission process causes the net speed of the electromagnetic wave to be less than c. This is observed in the animation below.

The actual speed of an electromagnetic wave through a material medium is dependent upon the optical density of that medium. Different materials cause a different amount of delay due to the absorption and reemission process. Furthermore, different materials have their atoms more closely packed and thus the amount of distance between atoms is less. These two factors are dependent upon the nature of the material through which the electromagnetic wave is traveling. As a result, the speed of an electromagnetic wave is dependent upon the material through which it is traveling.

For more information on physical descriptions of waves, visit The Physics Classroom Tutorial . Detailed information is available there on the following topics:

Mechanical vs. Electromagnetic Waves Wavelike Behaviors of Light The EM and Visible Spectra Light Absorption, Reflection, and Transmission Optical Density and Light Speed  

Return to List of Animations

Can Humans Hear Sound in Space?

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Is it possible to hear sounds in space? The short answer is "No." Yet, misconceptions about sound in space continue to exist, mostly due to the sound effects used in sci-fi movies and TV shows. How many times have we "heard" the starship Enterprise or the Millennium Falcon whoosh through space? It's so ingrained our ideas about space that people are often surprised to find out that it doesn't work that way. The laws of physics explain that it can't happen, but often enough producers don't really think about them. They're going for "effect."

Plus, it's not just a problem in TV or movies. There are mistaken ideas out there that planets make sounds , for example. What's really happening is that specific processes in their atmospheres (or rings) are sending out emissions that can be picked up by sensitive instruments. In order to understand them, scientists take the emissions and "heterodyne" them (that is, process them) to create something we can "hear" so they can try to analyze what they are. But, the planets themselves aren't making sounds.

The Physics of Sound

It is helpful to understand the physics of sound. Sound travels through the air as waves. When we speak, for example, the vibration of our vocal cords compresses the air around them. The compressed air moves the air around it, which carries the sound waves. Eventually, these compressions reach the ears of a listener, whose brain interprets that activity as sound. If the compressions are high frequency and moving fast, the signal received by the ears is interpreted by the brain as a whistle or a shriek. If they're lower frequency and moving more slowly, the brain interprets it as a drum or a boom or a low voice.

Here's the important thing to remember: without anything to compress, sound waves can't be transmitted. And, guess what? There's no "medium" in the vacuum of space itself that transmits sound waves. There is a chance that sound waves can move through and compress clouds of gas and dust, but we wouldn't be able to hear that sound. It would be too low or too high for our ears to perceive. Of course, if someone were in space without any protection against the vacuum, hearing any sound waves would be the least of their problems. 

Light waves (that aren't radio waves) are different. They do not require the existence of a medium in order to propagate. So light can travel through the vacuum of space unimpeded. This is why we can see distant objects like planets , stars , and galaxies . But, we can't hear any sounds they might make. Our ears are what pick up sound waves, and for a variety of reasons, our unprotected ears aren't going to be in space.

Haven't Probes Picked Up Sounds From the Planets?

This is a bit of a tricky one. NASA, back in the early 90s, released a five-volume set of space sounds. Unfortunately, they were not too specific about how the sounds were made exactly. It turns out the recordings weren't actually of sound coming from those planets. What was picked up were interactions of charged particles in the magnetospheres of the planets; trapped radio waves and other electromagnetic disturbances. Astronomers then took these measurements and converted them into sounds. It is similar to the way that a radio captures the radio waves (which are long-wavelength light waves) from radio stations and converts those signals into sound.

Why Apollo Astronauts Report Sounds Near the Moon

This one is truly strange. According to NASA transcripts of the Apollo moon missions, several of the astronauts reported hearing "music" when orbiting the Moon . It turns out that what they heard was entirely predictable radio frequency interference between the lunar module and the command modules.

The most prominent example of this sound was when the Apollo 15 astronauts were on the far side of the Moon. However, once the orbiting craft was over the near side of the Moon, the warbling stopped. Anyone who has ever played with a radio or done HAM radio or other experiments with radio frequencies would recognize the sounds at once. They were nothing abnormal and they certainly didn't propagate through the vacuum of space. 

Why Movies Have Spacecrafts Making Sounds

Since we know that no one can physically hear sounds in the vacuum of space, the best explanation for sound effects in TV and movies is this: if producers didn't make the rockets roar and the spacecraft go "whoosh", the soundtrack would be boring. And, that's true. It doesn't mean there's sound in space. All it means is that sounds are added to give the scenes a little drama. That's perfectly fine as long as people understand it doesn't happen in reality. 

• Can a Planet Make a Sound in Space?
• Where Does Space Begin?
• How Radio Waves Help Us Understand the Universe
• The History of Radio Technology
• 10 Sounds We Hate Most
• Neil Armstrong Quotes
• Michael Collins, Astronaut Who Piloted Apollo 11's Command Module
• A Kids' Guide to Making Your Own Metal Detector
• Light and Astronomy
• The Space Race of the 1960s
• RADAR and Doppler RADAR: Invention and History
• Learn About the True Speed of Light and How It's Used
• Bringing Humans to Mars is a Challenge
• Images of Earth From Outer Space
• How Do Tides and Waves Work?
• The Top Space Questions

Anatomy of an Electromagnetic Wave

Energy, a measure of the ability to do work, comes in many forms and can transform from one type to another. Examples of stored or potential energy include batteries and water behind a dam. Objects in motion are examples of kinetic energy. Charged particles—such as electrons and protons—create electromagnetic fields when they move, and these fields transport the type of energy we call electromagnetic radiation, or light.

What are Electromagnetic and Mechanical waves?

Mechanical waves and electromagnetic waves are two important ways that energy is transported in the world around us. Waves in water and sound waves in air are two examples of mechanical waves. Mechanical waves are caused by a disturbance or vibration in matter, whether solid, gas, liquid, or plasma. Matter that waves are traveling through is called a medium. Water waves are formed by vibrations in a liquid and sound waves are formed by vibrations in a gas (air). These mechanical waves travel through a medium by causing the molecules to bump into each other, like falling dominoes transferring energy from one to the next. Sound waves cannot travel in the vacuum of space because there is no medium to transmit these mechanical waves.

ELECTROMAGNETIC WAVES

Electricity can be static, like the energy that can make your hair stand on end. Magnetism can also be static, as it is in a refrigerator magnet. A changing magnetic field will induce a changing electric field and vice-versa—the two are linked. These changing fields form electromagnetic waves. Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate. This means that electromagnetic waves can travel not only through air and solid materials, but also through the vacuum of space.

In the 1860's and 1870's, a Scottish scientist named James Clerk Maxwell developed a scientific theory to explain electromagnetic waves. He noticed that electrical fields and magnetic fields can couple together to form electromagnetic waves. He summarized this relationship between electricity and magnetism into what are now referred to as "Maxwell's Equations."

Heinrich Hertz, a German physicist, applied Maxwell's theories to the production and reception of radio waves. The unit of frequency of a radio wave -- one cycle per second -- is named the hertz, in honor of Heinrich Hertz.

His experiment with radio waves solved two problems. First, he had demonstrated in the concrete, what Maxwell had only theorized — that the velocity of radio waves was equal to the velocity of light! This proved that radio waves were a form of light! Second, Hertz found out how to make the electric and magnetic fields detach themselves from wires and go free as Maxwell's waves — electromagnetic waves.

WAVES OR PARTICLES? YES!

Light is made of discrete packets of energy called photons. Photons carry momentum, have no mass, and travel at the speed of light. All light has both particle-like and wave-like properties. How an instrument is designed to sense the light influences which of these properties are observed. An instrument that diffracts light into a spectrum for analysis is an example of observing the wave-like property of light. The particle-like nature of light is observed by detectors used in digital cameras—individual photons liberate electrons that are used for the detection and storage of the image data.

POLARIZATION

One of the physical properties of light is that it can be polarized. Polarization is a measurement of the electromagnetic field's alignment. In the figure above, the electric field (in red) is vertically polarized. Think of a throwing a Frisbee at a picket fence. In one orientation it will pass through, in another it will be rejected. This is similar to how sunglasses are able to eliminate glare by absorbing the polarized portion of the light.

DESCRIBING ELECTROMAGNETIC ENERGY

The terms light, electromagnetic waves, and radiation all refer to the same physical phenomenon: electromagnetic energy. This energy can be described by frequency, wavelength, or energy. All three are related mathematically such that if you know one, you can calculate the other two. Radio and microwaves are usually described in terms of frequency (Hertz), infrared and visible light in terms of wavelength (meters), and x-rays and gamma rays in terms of energy (electron volts). This is a scientific convention that allows the convenient use of units that have numbers that are neither too large nor too small.

The number of crests that pass a given point within one second is described as the frequency of the wave. One wave—or cycle—per second is called a Hertz (Hz), after Heinrich Hertz who established the existence of radio waves. A wave with two cycles that pass a point in one second has a frequency of 2 Hz.

Electromagnetic waves have crests and troughs similar to those of ocean waves. The distance between crests is the wavelength. The shortest wavelengths are just fractions of the size of an atom, while the longest wavelengths scientists currently study can be larger than the diameter of our planet!

An electromagnetic wave can also be described in terms of its energy—in units of measure called electron volts (eV). An electron volt is the amount of kinetic energy needed to move an electron through one volt potential. Moving along the spectrum from long to short wavelengths, energy increases as the wavelength shortens. Consider a jump rope with its ends being pulled up and down. More energy is needed to make the rope have more waves.

Next: Wave Behaviors

National Aeronautics and Space Administration, Science Mission Directorate. (2010). Anatomy of an Electromagnetic Wave. Retrieved [insert date - e.g. August 10, 2016] , from NASA Science website: http://science.nasa.gov/ems/02_anatomy

Science Mission Directorate. "Anatomy of an Electromagnetic Wave" NASA Science . 2010. National Aeronautics and Space Administration. [insert date - e.g. 10 Aug. 2016] http://science.nasa.gov/ems/02_anatomy

Discover More Topics From NASA

James Webb Space Telescope

Perseverance Rover

Parker Solar Probe

Sounds in space: What noises do planets make?

From Martian winds to Saturn’s aurora, how sounds in space add to our understanding of the universe.

• Sounds of Earth’s magnetosphere

Sounds of Jupiter and Saturn

Landers with microphones.

• Comet encounter

Additional resources

Bibliography.

In 2022, people on Earth were able to hear the planetary sounds of Mars thanks to two microphones installed on board NASA's Perseverance rover. The audio clips of these sounds in space captured range from a gust of Martian wind to the snapping sound of the rover’s laser hitting a rock. 

According to NASA , these sounds are subtly different from what you would hear on Earth , being quieter and more muffled due to the lower density and different composition of the Martian atmosphere . Even so, anyone expecting other planets to sound truly "alien" might be disappointed by just how ordinary Perseverance's recordings sound.

But there are other possibilities. The planetary sounds we hear, are wavelike vibrations of air molecules occurring within the range of frequencies to which  our ears are sensitive, according to the BBC . 

However, it's possible to process any other kind of wave or oscillation electronically, scaling it to audible frequencies and then converting it into a sound wave. This can be done with virtually any type of astronomical data, often with distinctly spooky results . The process of turning non-acoustic data into audible sounds — called sonification — can have benefits for astronomers involved in analyzing the data, according to Scientific American .

— What does space sound like? Explore the sounds of Netflix's 'Away'

— Space roar: NASA detected the loudest sound in the universe, but what is it?

— Earth's Magnetic Field Booms Like a Drum, But No One Can Hear It

One of the best known examples came from the European Space Agency (ESA)'s Rosetta mission to comet 67P/Churyumov–Gerasimenko . This particular sonification, released during the encounter in Nov. 2014, was based on low-frequency oscillations in the comet 's magnetic field, which were then scaled up by a factor of 10,000 to make them audible, according to ESA . 

Called "The Singing Comet" and heard over 5 million times, this was one of the first pure audio clips to go viral when it was posted on SoundCloud, according to National Public Radio .

Another promising source of outer space "sound" is radio astronomy . One of the first uses of radio here on Earth was for sound broadcasting, and just as an audio signal can be carried by a radio wave , so radio telescope data can be transformed into audible sounds. One of the pioneers of "acoustic astronomy" is Fiorella Terenzi, who used it  initially as an aid to data analysis, and later as a form of science outreach. 

According to Popular Mechanics , Terenzi began converting radio waves from distant galaxies into audio form when she was a student in 1987. Now a professor at Florida International University, Terenzi has applied similar techniques to other astronomical data, including radio emissions from the planets Jupiter and Saturn and the Earth's own magnetosphere. A selection of audio clips can be heard on her website .

While ground-based radio telescopes listen in on signals originating vast distances away, sensors fitted to interplanetary spacecraft can "hear" radio waves — and other types of signal — in situ. Here we take a brief look at some of the otherworldly sounds that have been recorded.

Sounds of Earth's magnetosphere

When NASA's Juno spacecraft crossed the boundary between interplanetary space and Jupiter’s magnetosphere in 2016, there was an abrupt change in the electric field measurements it recorded, according to NASA . In a YouTube video from NASA’s Jet Propulsion Laboratory , these measurements were converted into sound waves, which brought out the dramatic nature of the change much more vividly than a conventional graphical representation.

More than a decade earlier, NASA released another striking audio clip , in this case made by the Cassini probe to Saturn. This eerie recording, displaying an amazing range of variations in both frequency and time, is derived from the planet’s radio emissions. These are closely related to Saturn's aurora , which, like the Earth’s, occur around the poles of the planet.

When NASA’s Perseverance rover picked up the sounds of Mars  in Feb. 2021, it was the first to do so – but only just. Soon after, China released audio recordings made by its own Mars rover , Zhurong, Space.com reported at the time. Now we have a good idea what the Red Planet sounds like – but what about other places that have atmospheres thick enough to carry sound waves?

The Soviet Union’s Venera 13, which landed on Venus in March 1982, was the first spacecraft to record sounds on another planet. These include both the Venusian wind and the sound of the probe itself hitting the ground. Later, the European Space Agency’s Huygens lander carried a microphone on its descent through the atmosphere of Saturn’s moon Titan .

Sounds of a comet encounter

The electromagnetic sounds recorded by Rosetta on its cometary encounter required considerable processing to make them audible to human ears. But when an earlier probe, NASA's Stardust , flew past comet Tempel 1 in 2011, it "heard" something much closer to real sounds. 

While sound waves can't travel through space, dust grains and larger debris breaking off the comet could be heard when they hit the probe’s protective shield. According to NASA , around 5,000 impacts were detected over an 11 minute period as the spacecraft was pelted by fragments of dust and ice.

You can listen to a selection of sounds recorded in space, including the song of the sun and Cassini-Huygens passing through Saturn's rings, at ESA's website . Find out how musician Mickey Hart produced music using frequencies from space in this article from Smithsonian . 

• " Heavenly Sounds: Hearing Astronomical Data Can Lead to Scientific Insights ". Scientific American (2014). 
• Terenzi, F. " Acoustic Astronomy: The Sounds of the Universe, Audiofication/Sonification of Celestial Data ". Florida International University.
• Mössinger, J.C. " Sounds from space ". Nature (2003).
• " The interaction between the solar wind and the Earth's magnetosphere ". The Journal of Geophysical Research (1962).

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Andrew May holds a Ph.D. in astrophysics from Manchester University, U.K. For 30 years, he worked in the academic, government and private sectors, before becoming a science writer where he has written for Fortean Times, How It Works, All About Space, BBC Science Focus, among others. He has also written a selection of books including Cosmic Impact and Astrobiology: The Search for Life Elsewhere in the Universe, published by Icon Books.

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Course: physics library   >   unit 14, light: electromagnetic waves, the electromagnetic spectrum and photons.

• Electromagnetic waves and the electromagnetic spectrum
• Polarization of light, linear and circular

Introduction to electromagnetic waves

Basic properties of waves: amplitude, wavelength, and frequency, example: calculating the wavelength of a light wave, the electromagnetic spectrum, quantization of energy and the dual nature of light, example: calculating the energy of a photon, attributions.

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Is There Sound in Space?

No, there is no sound in space. At least, not in the way we traditionally understand sound on Earth. The misconception exists largely due to popular culture. Movies and TV shows often depict space battles with roaring rockets and booming exploding stars, but in reality, space is eerily silent.

The reason for this silence lies in the nature of sound itself. Sound is a vibration that travels through a medium, like air or water. For sound waves to propagate, they need particles. Space is a near- perfect vacuum , meaning it has very few particles. Without a medium for these sound waves, there is no sound.

NASA’s “Space Sounds”: Understanding Sonification

Despite the silence of space, there are videos and recordings labeled as “sounds from space” released by NASA. These are not sounds in the traditional sense. Instead, they are products of a process called sonification.

Sonification is the conversion of data into sound. In the context of space, instruments on spacecraft record electromagnetic vibrations or particle interactions. These signals, which are not audible, get converted into sound waves that we can hear. When scientists represent data in an auditory format, it makes certain patterns and anomalies easier to detect.

For instance, the eerie “whistles” and “howls” from recordings of Jupiter or Saturn aren’t sounds that an astronaut could hear. Instead, they are sonifications of radio waves or other electromagnetic phenomena detected by spacecraft.

Gravitational Waves: A Type of Sound in Space

The groundbreaking discovery of gravitational waves adds a new layer to our understanding of “sounds” in space. Detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO), these are ripples in spacetime caused by cataclysmic events, like the merging of two black holes.

Now, gravitational waves aren’t sounds in the traditional sense. They don’t propagate through air or water; they literally stretch and compress the fabric of the universe. However, much like the sonifications mentioned earlier, scientists often convert gravitational wave data into sound.

When scientists at LIGO do this, the results are astounding. The final moments of two black holes spiraling into one another can be “heard” as a chirp. In this context, these gravitational waves are akin to the universe’s symphony, a testament to the colossal events unfolding in the cosmos.

Sound in Space: Can You Hear Sound on the Moon?

Similar to the vastness of space, the Moon is also an environment where sound doesn’t propagate in the traditional manner. The Moon has an extremely thin atmosphere or exosphere, which consists of very few particles. Because of this near- vacuum condition, there’s no medium for sound waves to travel through on the Moon’s surface. So, if an astronaut shouts on the Moon without any equipment, the sound doesn’t travel. Another astronaut standing a distance can’t hear it.

How Astronauts Talk on the Moon

Given the lack of an effective medium for sound transmission on the Moon, you might wonder how astronauts communicate with each other. Astronauts wear helmets that are part of a sealed system, connected to their spacesuits. Inside these helmets, there’s an atmosphere – usually a mix of oxygen and other gases – which transmits sound. When an astronaut speaks, the sound waves travel through the air inside the helmet, reaching a microphone. This microphone then converts the sound into an electrical signal, which transmits the signal to the communication systems of other astronauts or to mission control on Earth.

Any vibrations caused by an astronaut’s activities on the Moon are felt through their spacesuit. If an astronaut taps on another’s helmet, the latter “hears” it through the vibrations conducted by their spacesuit and helmet.

The Mysterious Music of Apollo

During the Apollo 10 mission, astronauts reported hearing a strange “whistling” sound, which some described as “outer-space-type music,” while they were orbiting the dark side of the Moon. This event remained classified until 2008 and spurred numerous speculations and theories.

However, the source of this “music” wasn’t extraterrestrial. The sounds were likely radio interference between the lunar module and the command module of the spacecraft. When two radios are close to each other and set to similar frequencies, they produce a whistling sound due to interference. This phenomenon, while eerie in the context of space exploration, is quite common and has a straightforward scientific explanation.

Sound on Mars

Mars has a very thin atmosphere composed mainly of carbon dioxide, with traces of nitrogen and argon. This atmosphere is about 100 times less dense than Earth’s. The atmospheric pressure at the Martian surface averages 0.6% of Earth’s sea level pressure. Such a tenuous atmosphere significantly affects the way sound travels on Mars compared to Earth.

Sound travels through the movement of particles in a medium, be it solid, liquid, or gas. The speed and character of sound waves are influenced by the properties of this medium. Given Mars’ thin atmosphere, sound travels slower than it does on Earth. Additionally, the composition of the Martian atmosphere means that certain frequencies, especially higher ones, get absorbed more quickly and do not travel as far.

In practical terms, this means that sounds on Mars are quieter and muffled than we’re used to. High-pitched noises are particularly hard to hear. If you were to have a conversation on Mars without the aid of communication equipment, voices would sound different, and you’d need to be much closer to the source of a sound to hear it clearly.

Are Wind and Dust Storms Silent?

Mars has frequent wind events and massive dust storms. But would a human standing on the Martian surface hear these?

Wind on Mars, even during a strong gust, sounds very faint. Given the thin atmosphere, there simply aren’t enough particles colliding with one another to produce a sound as loud as on Earth.

The massive dust storms that engulf the entire planet are visually impressive, but are surprisingly quiet. The movement of the fine dust and the thin atmosphere does not generate the roaring sounds we associate with storms on Earth. Instead, you might hear a soft hiss or a very low rumble, but it would be much subtler than one might expect.

• Abbott, R.; et al. (29 June 2021). “Observation of Gravitational Waves from Two Neutron Star–Black Hole Coalescences”. The Astrophysical Journal Letters . 915 (1): L5. doi: 10.3847/2041-8213/ac082e
• Everest, F. (2001).  The Master Handbook of Acoustics . New York: McGraw-Hill. ISBN 978-0-07-136097-5.
• Kinsler, L.E.; Frey, A.R.; Coppens, A.B.; Sanders, J.V. (2000).  Fundamentals of Acoustics  (4th ed.). New York: John Wiley & Sons. ISBN 0-471-84789-5.
• Maurice, S.; et al. (2022). “In situ recording of Mars soundscape:. Nature. 605: 653-658. doi: 10.1038/s41586-022-04679-0

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Why isn’t there any sound in space? An astronomer explains why in space no one can hear you scream

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How far can sound travel through space, since it’s so empty? Is there an echo in space? – Jasmine, age 14, Everson, Washington

In space, no one can hear you scream.

You may have heard this saying. It’s the tagline from the famous 1979 science fiction movie “ Alien .” It’s a scary thought, but is it true? The simple answer is yes, no one can hear you scream in space because there is no sound or echo in space.

I’m a professor of astronomy , which means I study space and how it works. Space is silent – for the most part.

How sound works

To understand why there’s no sound in space, first consider how sound works. Sound is a wave of energy that moves through a solid, a liquid or a gas.

Sound is a compression wave . The energy created when your vocal cords vibrate slightly compresses the air in your throat, and the compressed energy travels outward.

A good analogy for sound is a Slinky toy . If you stretch out a Slinky and push hard on one end, a compression wave travels down the Slinky.

When you talk, your vocal cords vibrate. They jostle air molecules in your throat above your vocal cords, which in turn jostle or bump into their neighbors, causing a sound to come out of your mouth.

Sound moves through air the same way it moves through your throat. Air molecules near your mouth bump into their neighbors, which in turn bump into their neighbors, and the sound moves through the air. The sound wave travels quickly , about 760 miles per hour (1,223 kilometers per hour), which is faster than a commercial jet.

Space is a vacuum

So what about in space?

Space is a vacuum, which means it contains almost no matter. The word vacuum comes from the Latin word for empty .

Sound is carried by atoms and molecules. In space, with no atoms or molecules to carry a sound wave, there’s no sound. There’s nothing to get in sound’s way out in space, but there’s nothing to carry it, so it doesn’t travel at all. No sound also means no echo. An echo happens when a sound wave hits a hard, flat surface and bounces back in the direction it came from.

By the way, if you were caught in space outside your spacecraft with no spacesuit, the fact that no one could hear your cry for help is the least of your problems. Any air you still had in your lungs would expand because it was at higher pressure than the vacuum outside. Your lungs would rupture. In a mere 10 to 15 seconds , you’d be unconscious due to a lack of oxygen.

Sound in the solar system

Scientists have wondered how human voices would sound on our nearest neighboring planets, Venus and Mars. This experiment is hypothetical because Mars is usually below freezing , and its atmosphere is thin, unbreathable carbon dioxide . Venus is even worse – its air is hot enough to melt lead, with a thick carbon dioxide atmosphere.

On Mars, your voice would sound tinny and hollow, like the sound of a piccolo . On Venus , the pitch of your voice would be much deeper, like the sound of a booming bass guitar. The reason is the thickness of the atmosphere. On Mars the thin air creates a high-pitched sound, and on Venus the thick air creates a low-pitched sound. The team that worked this out simulated other solar system sounds , like a waterfall on Saturn’s moon Titan.

Deep space sounds

While space is a good enough vacuum that normal sound can’t travel through it, it’s actually not a perfect vacuum, and it does have some particles floating through it.

Beyond the Earth and its atmosphere, there are five particles in a typical cubic centimeter – the volume of a sugar cube – that are mostly hydrogen atoms. By contrast, the air you are breathing is 10 billion billion (10 19) times more dense. The density goes down with distance from the Sun, and in the space between stars there are 0.1 particles per cubic centimeter. In vast voids between galaxies , it is a million times lower still – fantastically empty.

The voids of space are kept very hot by radiation from stars. The very spread-out matter found there is in a physical state called a plasma .

A plasma is a gas in which electrons are separated from protons. In a plasma, the physics of sound waves get complicated . Waves travel much faster in this low-density medium, and their wavelength is much longer.

In 2022, NASA released a spectacular example of sound in space . It used X-ray data to make an audible recording that represents the way a massive black hole stirs up plasma in the Perseus galaxy cluster, 250 million light years from Earth. The black hole itself emits no sound, but the diffuse plasma around it carries very long wavelength sound waves.

The natural sound is far too low a frequency for the human ear to hear, 57 octaves below middle C, which is the middle note on a piano and in the middle of the range of sound people can hear. But after raising the frequency to the audible range, the result is chilling – it’s the sound of a black hole growling in deep space.

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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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Extended Response

13.1 types of waves.

• Sound waves are mechanical waves and require a medium to propagate. Light waves can travel through a vacuum.
• Sound waves are electromagnetic waves and require a medium to propagate. Light waves can travel through a vacuum.
• Light waves are mechanical waves and do not require a medium to propagate; sound waves require a medium to propagate.
• Light waves are longitudinal waves and do not require a medium to propagate; sound waves require a medium to propagate.
• No, the requirement of a medium for propagation does not depend on whether the waves are pulse waves or periodic waves.
• Yes, the requirement of a medium for propagation depends on whether the waves are pulse waves or periodic waves.
• Sound waves in solids are transverse, whereas in air, they are longitudinal.
• Sound waves in solids are longitudinal, whereas in air, they are transverse.
• Sound waves in solids can be both longitudinal and transverse, whereas in air, they are longitudinal.
• Sound waves in solids are longitudinal, whereas in air, they can be both longitudinal and transverse.

13.2 Wave Properties: Speed, Amplitude, Frequency, and Period

• The gull experiences mostly side-to-side motion and moves with the wave in its direction.
• The gull experiences mostly side-to-side motion but does not move with the wave in its direction.
• The gull experiences mostly up-and-down motion and moves with the wave in its direction.
• The gull experiences mostly up-and-down motion but does not move in the direction of the wave.
• In a good-quality speaker, sounds with high frequencies or short wavelengths are reproduced accurately by woofers, while sounds with low frequencies or long wavelengths are reproduced accurately by tweeters.
• Sounds with high frequencies or short wavelengths are reproduced more accurately by tweeters, while sounds with low frequencies or long wavelengths are reproduced more accurately by woofers.

The time difference between a 2 km/s S-wave and a 6 km/s P-wave recorded at a certain point is 10 seconds. How far is the epicenter of the earthquake from that point?

13.3 Wave Interaction: Superposition and Interference

• The crests and the troughs of waves traveling in the same direction combine to form a criss-cross pattern.
• The crests and the troughs of waves traveling in different directions combine to form a criss-cross pattern.
• pure constructive interference
• pure destructive interference
• a combination of constructive and destructive interference
• Destructive interference results in waves with greater amplitudes being formed in places farther away from the epicenter.
• Constructive interference results in waves with greater amplitudes being formed in places farther away from the epicenter.
• The standing waves of great amplitudes are formed in places farther away from the epicenter.
• The pulse waves of great amplitude are formed in places farther away from the epicenter.
• The glass and the water reflect the light in different directions. Hence, the object appears to be distorted.
• The glass and the water absorb the light by different amounts. Hence, the object appears to be distorted.
• Water, air, and glass are media with different densities. Light rays refract and bend when they pass from one medium to another. Hence, the object appears to be distorted.
• The glass and the water disperse the light into its components. Hence, the object appears to be distorted.

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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

MSU Extension

Exploring our world: how does sound travel.

Tracy D'Augustino <[email protected]> , Michigan State University Extension - March 22, 2018

Have you ever wondered how sound travels? Help youth ask questions and discover answers about sound by using these activities.

How does sound travel? Does sound travel differently than light? The  Michigan State University Extension  science team’s goal is to increase science literacy across Michigan. One way we increase interest in science is to provide information and ideas for engaging youth in the exploration of their world. Adults can help youth increase their science literacy by encouraging them to   ask questions and discover answers . Exploring sound is just one way to engage youth in STEM (Science, Technology, Engineering and Mathematics).

Ask youth how they think sound travels. Does it travel the same way light does? Why or why not? Provide youth with a piece of rope and challenge them to make a wave by moving one end of the rope while the other end is stationary by being tied to a nail or doorknob. Youth should shake one end of the rope making an “S”-shaped wave that travels the length of the rope. Ask youth if the wave travels in the same direction as the movement used to make it.

Tie a colored ribbon at one point in the rope. Notice how the ribbon moves up and down, but not forward and backward on the rope. As they watch the wave, youth should realize that while they are shaking the rope up and down, the wave they create is traveling away, perpendicular to their motion—not up or down. This is a transverse wave; a wave that undulates perpendicular to the direction of propagation. Light waves are transverse waves.

Next, give youth a large spring, like a slinky, and have them stretch it out along a table. Ask them to make a wave without shaking it like they did the rope. Youth should discover they can make a wave in a spring by compressing, or pinching, a couple of the coils together then releasing them. Ask youth if the wave travels in the same direction as the movement used to make it. As they watch the wave, they should realize the wave they are making is traveling in the same direction as the motion they used to make it. This is a compression wave; longitudinal or compression waves undulate in the direction of propagation. Sound waves are compression waves.

While sound and light travel in similar ways as waves, do they travel similarly through the same types of matter? Ask youth to brainstorm and make a list of things sound can travel through. Help ensure they think about the three states of matter: solid, liquid and gas. Next, ask them to decide which of the items listed light can travel through. For more information about how sound travels through different materials read , “ Can you hear better underwater? ”

What about in outer space? Do you think light travels through outer space? Why or why not? Do you think sound travels through outer space? Why or why not? Youth should discover that sound waves can travel through more materials than light waves. Light waves or transverse waves can travel through the vacuum of space while sound waves or compression waves require a medium in which to travel.

Ask youth what they think travels faster: sound or light. Why do they think one is faster than the other? Can they recall evidence, something they’ve seen or heard, that makes them think the way they do? Allow time for youth to discuss their ideas and evidence.

Give one youth a metal cookie sheet and stick. Have them take the sheet and stick across a field or down a long driveway, about 100 yards away. Ask the youth with the cookie sheet to hold their arms straight out from their sides, cookie sheet in one hand and stick in the other. Next, bring their hands together over their head, strike the cookie sheet and bring their arms down again. Did the youth see the arms come back down before they heard the sound?

MSU Extension  and the  Michigan 4-H  Youth Development program help to create a community excited about STEM (Science, Technology, Engineering, and Mathematics). 4-H STEM programming seeks to increase science literacy, introducing youth to the experiential learning process that helps them to build problem-solving, critical-thinking and decision-making skills. Youth who participate in 4-H STEM are better equipped with critical life skills necessary for future success.

To learn more about the positive impact of Michigan 4-H youth in  STEM literacy  programs, read our 2016 Impact Report: “ Building Science Literacy and Future STEM Professionals .”

To learn more about MSU Extension, visit the  MSU Extension  website. To learn more about 4-H and Extension opportunities in Alcona County, stop by our Harrisville office at 320 S. State St. Harrisville, MI 48740, or visit us online at our  Alcona County MSU Extension Facebook page  or  Alcona County Extension office  page.

This article was published by Michigan State University Extension . For more information, visit https://extension.msu.edu . To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters . To contact an expert in your area, visit https://extension.msu.edu/experts , or call 888-MSUE4MI (888-678-3464).

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• children and youth
• msu extension
• science & engineering
• children and youth,
• msu extension,

How Does Light Travel Through Space? Facts & FAQ

Last Updated on Mar 15 2024

Light is such a fundamental part of our lives. From the moment we’re born, we are showered with all kinds of electromagnetic radiation, both colorful, and invisible. Light travels through the vacuum of space at 186,828 miles per second as transverse waves , outside of any material or medium, because photons—the particles that make up light—also behave as waves. This is referred to as the wave-particle duality of light.  

• What Is Light?

The wave-particle duality of light simply means that light behaves as both waves and particles . Although this has been long accepted as fact, scientists only managed to observe both these properties of light ¹ simultaneously for the first time in 2015.

As a wave, light is electromagnetic radiation—vibrations, or oscillations, of the electric and magnetic fields. As particles, light is made up of little massless packets of energy called photons ¹ .

• What Are Light Waves?

Waves are the transference of energy from one point to another. If we dropped a pebble into a small pond, the energy that the impact creates would transfer as a ripple, or a wave, that travels through the surface of the water, from one water particle to another, until eventually reaching the edge of the pond.

This is also how sound waves work—except that, with sound, it’s the pressure or vibrations of particles in the air that eventually reach our ears.

Unlike water and sound, light itself is electromagnetic radiation—or light waves—so it doesn’t need a medium to travel through.

• What Are Transverse Waves?

Light propagates through transverse waves. Transverse waves refer to a way in which energy is transferred.

Transverse waves oscillate at a 90-degree angle (or right angle) to the direction the energy is traveling in. An easy way to picture this is to imagine an S shape flipped onto its side. The waves would be going up and down, while the energy would be moving either left or right.

With light waves ¹ , there are 2 oscillations to consider. If the light wave is traveling on the X axis, then the oscillations of the electric field would be at a right angle, either along the Y or Z axes, and the oscillations of the magnetic field would be on the other.

• Can Anything Travel Faster Than Light?

The simple answer to this question is no, as far as we know at this time, nothing can go faster than the speed of light ¹ . Albert Einstein’s special theory of relativity states that “no known object can travel faster than the speed of light in a vacuum.”

Space and time don’t yet exist beyond the speed of light—if we were to travel that fast, the closer we get to the speed of light, the more our spatial dimension would shrink, until eventually collapsing.

Beyond this, the laws of physics state that as an object approaches the speed of light , its mass would become infinite, and so would the energy it would need to propel it. Since it’s probably impossible to create an infinite amount of energy, it would be difficult for anything to travel faster than light.

Tachyon, a hypothetical particle, is said to travel faster than the speed of light. However, because its speed would not be consistent with the known laws of physics, physicists believe that tachyon particles do not exist.

• Final Thoughts

Light travels through space as transverse, electromagnetic waves. Its wave-particle duality means that it behaves as both particles and waves. As far as we know, nothing in the world travels as fast as light.

• https://phys.org/news/2015-03-particle.html
• https://www.nature.com/articles/ncomms7407
• https://www.wtamu.edu/~cbaird/sq/2017/07/20/is-the-reason-that-nothing-can-go-faster-than-light-because-we-have-not-tried-hard-enough/
• https://www.physics.brocku.ca/PPLATO/h-flap/phys6_1f_1.png
• https://science.nasa.gov/ems/02_anatomy

Featured Image Credit: NASA, Unsplash

Table of Contents

About the Author Cheryl Regan

Cheryl is a freelance content and copywriter from the United Kingdom. Her interests include hiking and amateur astronomy but focuses her writing on gardening and photography. If she isn't writing she can be found curled up with a coffee and her pet cat.

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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-2l0eat{font-family:UnitedSans,UnitedSans-roboto,UnitedSans-local,Helvetica,Arial,Sans-serif;font-size:1.625rem;line-height:1.2;margin:0rem;padding:0.9rem 1rem 1rem;}@media(max-width: 48rem){.css-2l0eat{font-size:1.75rem;line-height:1;}}@media(min-width: 48rem){.css-2l0eat{font-size:1.875rem;line-height:1;}}@media(min-width: 64rem){.css-2l0eat{font-size:2.25rem;line-height:1;}}.css-2l0eat b,.css-2l0eat strong{font-family:inherit;font-weight:bold;}.css-2l0eat em,.css-2l0eat i{font-style:italic;font-family:inherit;} 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. 

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