Science Questions

How close would you have to be to the sun to be at room temperature?

If outer space is really cold, and the Sun is really hot, how close would you have to get to the Sun in order to be about room temperature? Fred and Scott, Cambridge

[We put this question to Carolin Crawford as part of the Planets and Cosmology show]

Carolin Crawford: Room temperature where on the Earth?

Chris: They don’t specify, so I guess you have full degrees of freedom, if you’ll pardon the pun.

Carolin: It’s difficult, because as you go up from the surface of the Earth, you get colder. Also, on the side of the Earth facing away from the Sun it will be different from the day side. It’s actually a very difficult question to answer as there’s so many different ways to approach it.

Chris: Recently there was a Swedish space walk, and they were talking about how when people are in space they must wear reflective space suits; because if they’re in the full glare of the Sun their body will quickly heat up to boiling point. In the dark side though, it’s very cold because you radiate the heat straight away again. So it is a difficult question to answer, because if you’re having sunlight hitting you, you soak up a lot of radiation, and if you’re out of direct sunlight, you’re not.

Carolin: Also, if you think about aeroplanes, you can see the condensation freezing on the outside of the aeroplane, and although you’re above the clouds, you’re still nowhere near space.

May 2007