by Claire Thoma Emmons
Research and Evaluation Associate

When Claire's not busy evaluating programs for The Children's Museum, she's also a science educator. Fun fact: Claire has a degree in astronomy!

When astronauts are out in space, they can whistle, talk, or even yell inside their own spacesuit, but the other astronauts would not hear the noise. 

In fact, the middle of space is very quiet. Sound travels in waves, and it moves at different speeds through air or water or other materials. But it has to have something to travel through or it won’t go anywhere at all.

Because there is nothing out in space (like an atmosphere), the sound waves from one astronaut’s whistling can't travel over to the other astronaut’s ears. That's why the astronauts use radios to communicate—even if they're floating in space right next to each other! 

When astronauts are inside the International Space Station, they're in a simulated atmosphere. It allows them to breathe without wearing space suits all the time. Inside the space station, sound waves travel like they do on Earth, and astronauts can whistle back and forth as much as they like—as long as they don’t annoy the other astronauts!