Kate: Hi! I’m Kate Powers from NIU STEM Outreach, joined by my good friend Sam Watt. Today we have a question from Annie who wants to know more about how scientists study stars from so far away. Well Annie, scientists listen to the stars, of course.
Sam: Um, that’s a confusing answer Kate. First, do stars…talk to us? Second, I thought space was a vacuum, and sound doesn’t travel through a vacuum.
Kate: Well, they don’t talk but they give off signals that communicate information to us. And you’re right Sam, sound waves require a medium, like air, to travel. The sounds we hear on Earth come from air molecules vibrating and bumping into each other, transferring energy from the source to our ear drums. Since there’s no air to vibrate in outer space, sound energy can’t travel through the vacuum the same way it does here on earth.
Sam: But you told Annie that scientists “listen” to objects in space to learn more about them. If there’s no sound in space, what are they listening to?
Kate: This is where it gets interesting. They’re listening to light!
Sam: Woah, woah --How do scientists listen to light?
Kate: Unlike sound, light does not need a medium to travel. Light can travel through the vacuum of space, no problem, and objects in space give off lots of different kinds of light. Some of that light is visible. But some is invisible, infrared and ultraviolet colors that are outside of our range of vision. Radio waves are an example of invisible waves.
Sam: So, objects in space give off radio waves, just like the tower here at the station.
Kate: Yep. And if we tune a radio receiver to the right frequency and point it towards those objects, it will transform those radio waves, which are a kind of light, into sounds that we hear.
Sam: What do scientists hope to learn by listening to these radio waves from space?
Kate: Even though they travel differently, sound waves and light waves still have a lot in common. Both have frequencies, which is how fast they’re changing, and both have amplitudes, which is how intense they are. Scientists study these waves to learn more about the objects that produce them. One thing that humans are still better at than computers is seeing and hearing patterns. By listening to the waves, or by turning them into visual information, scientists can detect subtle patterns that computers might overlook.
Sam: Thanks for the great question, Annie, and keep those awesome questions coming to STEMOutreach@niu.edu. This has been the Sound of Science on WNIJ.
Kate: Where you learn something new every day.