Amy’s Everyday Astronomy: Your Questions Answered – Radio Waves in Space

“How is it that things like planets, stars, and other things in space give off radio sounds?”

I love this question. It’s interesting to think that something like a planet or star would give off radio signals that can be recorded and heard. In fact, on YouTube there are several videos of the sounds of different planets and stars. They are eerie to listen to and I recommend doing so with headphones or earbuds.

In order to understand why and how this sound happens, one must first understand magnetic fields, which most planets and stars have.

The magnetic field of planets are usually, as far as scientists know, caused by the liquid of or near a planet’s core. So, for Earth, as an example, the core is solid nickel/iron but is surrounded by molten liquid. The churning of this liquid conducts electricity and has an electric charge.

Every planet’s magnetic field can differ depending on the core. So, in the case of Mars, the magnetic field is not contiguous around the planet’s entirety, likely because its core has solidified and there is no liquid surrounding it. This means that the ancient remnants of its magnetic field are only present in some areas of the planet, itself.

The magnetic field allows a given planet to maintain an atmosphere (and remain habitable if it’s in the goldilocks zone of its parent star).

Without such a field, the highly charged particles emanating from the parent star would blow the atmosphere away and cause other damage to the planet, making it completely uninhabitable. A lack of magnetic field will prevent a planet from producing and maintaining an ozone layer such as Earth’s, which keeps out the other harmful rays of the sun.

For stars, magnetic fields are formed differently.

Stellar magnetic fields are caused by the motion of conductive plasma produced inside a star. If you’ve ever seen pictures of the sun, you’d have noticed large loops of plasma that come out from the surface and go back down again. These regions are caused by the convection happening inside the star as the plasma heats and cools in circular patterns, rising and falling again within the star.

These cause localized areas of electromagnetism. Typically, where the magnetic activity is highest is the areas where we see sunspots.

As charged particles, like those emanating from a stellar body, come into contact with a planet or star’s magnetic field, those particles are accelerated. These speedy particles can give off radio emissions that can sound like whizzes, pops, tones, and even regular static.

Now I bet you’re wondering: “What about rogue planets? If they are not a part of a solar system and are just floating freely in space, do they give off radio signals?”

The answer is: Yes, they do.

Charged particles, like those that we talked about above, continue to travel through space. Remember Newton’s first law of physics: an object in motion tends to stay in motion unless acted upon by an outside force. This law applies to charged particles, as well. So, anything that emanated from a stellar body will continue to travel through space until it encounters something. And that includes rogue planets.

While the radio signals given off by this encounter will differ compared to that of any other body nearer to a star, there will still be something that can be recorded and heard.

In the end, any object in the cosmos that has a fluctuating magnetic field can produce radio waves. This means that anything, even asteroids and comets, can emit radio waves that can be detected.

If you’d like to hear some of the sounds recorded by NASA, you can do so by clicking here.

In the meantime, grab your lawn chairs and head outside on any given evening. While you can’t hear the radio signals with your own ears, you never know what you’ll see if you just keep your eyes to the skies.

Have a question about physics, astronomy, or a specific NASA mission? Email them to [email protected] and be sure to check out my Facebook page and website for all kinds of interesting information about the universe!


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