Radio: How Do We Hear Space?

There’s a lot of confusion I’ve seen on the internet about sound in space.

“if sound doesn’t travel in space, how do we pick up sound waves?” is a common question people ask, along with other similar questions. So what I’m going to do is explain how we “hear” space, and straighten out a few misconceptions.

 

Sound vs Light: What’s the difference?

Both light and sound are waves.

A wave is simply oscillating particles, which transfer energy. Although the particles move, they return back to their original position and don’t get carried along with the wave.

There are two types of waves: longitudinal and transverse.

Longitudinal waves oscillate parallel to the energy transfer. They’re made up of compressions (bits squashed together) and rarefactions (openly spaced bits). Longitudinal waves need a medium to travel through.

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Sound waves are longitudinal.

 

Transverse waves oscillate perpendicular to the energy transfer. They’re made of peaks, troughs. Transverse waves do not need a medium to travel through; they can travel through a vacuum (like space).

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Light (EM radiation) is transverse.

 

Does sound travel in space?

The short answer: no.

Sound is longitudinal, which means it needs a medium to travel through. Space is a vacuum, so there’s no way sound can actually travel through space.

Light is transverse, so it can travel through space. But you don’t need me telling you that; just look up at the night sky!

So both Death Star explosions were … inaccurate?

Yes buddy. Sorry to crush your childhood.

(Star wars is notorious for its scientific inaccuracy, but that doesn’t mean you shouldn’t watch it!)

So what are “Sound” Waves?

If we can’t pick up sound from space, what are we picking up?

Apart from visible light, we can’t see the rest of the electromagnetic spectrum (ultraviolet, microwaves, that stuff), but just like visible light we can still pick up these waves.

On one end of the EM spectrum lies radio waves. These are the longest types of radiation that exists, and can be picked up really easily by radio antennae and converted into sound. This is the sound astronomers talk about.

 

How do we pick them up?

With antennae!

Incoming radio waves hit the antenna and make electrons in the antenna oscillate, which induces a weak voltage and alternating current of a certain frequency. From that we can process the electric current and create sound.

Radio waves are used in so many things, like GPS, cell phones, wireless networks, and of course radios.

What does space sound like?

NASA has been using radio telescopes to pick up radio waves from various areas of space, most notably the planets.

Below is a compilation of radio waves picked up from objects in the solar system. Be warned, it is slightly unnerving, and Saturn is very loud!

 

That is all for now. Are there any interesting questions you want answered? Pop a comment below!

In the meantime, happy stargazing!

One comment

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