Science Questions

How cold is it in outer space and how do you protect satellites from extreme cold? Pamela in Georgia, USA

It's a bit of a fallacy that outer space is really cold. It actually depends on how close you are to the sun. One problem is that it doesn't feel cold like it does on the Earth. There's no air around you to conduct heat away from you or towards you; everything is done by radiation, passing light from one object to another. Light from the sun falls on a body and heats it up. For satellites up in space around Earth, we actually cover then in reflective material to keep them cool, and insulating material to keep them hot. If they're in the sunlight, they actually overheat so we put reflective material on there to reflect the light away. When they're in the Earth's shadow, we can use heaters to keep it warm. When you get further and further away from the sun, it gets really cold. The outer space around Earth is around 20 degrees Centigrade. If you go out to Pluto, you're probably looking at around minus 220 degrees Centigrade. So it depends on exactly where you are.

July 2006