Is it cold in space?

Question

I know it depends on where at in space. Lets say where satellites are, like right outside our atmopshere where they orbit...I was thinking it would be much colder since there is nothing to hold heat in such as our atmosphere.

Answer 1

The Question
(Submitted March 01, 1998)

All I wanted to ask you is that if we put a thermometer in Space with no other light or heat source around and absolutely no background radiation there, what would it read? Would the temperature be really cold or what?


The Answer
Yes, it would be really cold. Temperature measures the energy per "degree of freedom" (i.e. way something can move) of whatever molecules happen to be around. So, it it becomes so cold that the molecules stop all together, then this is the "absolute zero" temperature. On the Celsius Temperature Scale (i.e. water freezes at 0, and boils at 100) this takes place at -273 degrees C.
We usually use the Kelvin temperature scale, where Zero Kelvin is this "absolute zero" temperature -- or -273 degrees C. Water freezes at +273 Kelvin and water boils at +373 Kelvin.

If we put a thermometer in darkest space, with absolutely nothing around, it would first have to cool off. This might take a very very long time. Once it cooled off, it would read 2.7 Kelvin. This is because of the "3 degree microwave background radiation." No matter where you go, you cannot escape it -- it is always there.

Jonathan Keohane
for Ask an Astrophysicist

Answer 2

Matter reacts to degrees of space otherwise empty space is neither hot or cold,

Answer 3

Yes, it is cold in space because there is no matter (or very little) there!

It is a vacuum, and there is such little matter present that there is nothing that can absorb any energy from any heat source anywhere, so - you bet - it's a cold place.

Answer 4

The temperature in space is very low, but not zero. It has been measured very carefully and precisely. The average temperature out there is about 2.725 K. This is due to the cosmic background radiation left over from the big bang.

Answer 5

Your thinking is correct to a point. One one side of the satellite it is subfreezing, but the radiation from the sun on the sunny side of the satellite would fry your skin without the protection of a space suit.

Answer 6

Temperature is really just a measurement of how close atoms are together and how much heat is being transferred between them. Since atoms are miles apart in space, then the temperature would be extremely low.

Answer 7

It depends on where you are in relation to the sun's radiation. The sun's radiant heat would burn you up without the protection of the atmosphere.

Answer 8

Yep. It's about 3 degree Kelvin (-270 C).

Answer 9

In the sun, it's very hot. In the shade, it's very cold.

Answer 10

It's hard to imagine but it is neither hot or cold. there is no temperature in space just as there is no gravity.