Science Questions

Would space feel cold?

I've been wondering something for a long time: If someone went out into space and forgot to put on their space suit, would the person feel cold? Within the atmosphere, it feels cold if air blows across your skin, but in a vaccuum is it possible to feel cold? My guess is that the water in the person's skin would freeze and make them feel cold, but I really don't know. Thanks, Philip Phillip Hunt (via email)

Actually, the temperature is colder in space than on Earth, as we have an atmosphere which keeps us warm.  So at the same distance as the Earth from the Sun it’s about –50 degrees in space.  On Earth, we lose heat through radiation, evaporation of sweat and by conduction of heat to the air.  It is harder to lose heat in space as you can only lose heat through radiation.  Electrons in the molecules in our body go from a high energy state to a low energy state, and so lose energy by radiating infra-red radiation.  

When you face the sun, you will absorb the Sun’s radiation and be warm, but at the same time, your back will be in shade and will lose heat rapidly as there’s no atmosphere to conduct the heat around you.  Large temperature gradients are found in space; things get very hot when they are in the Sun’s rays, but very cold when they are in shade.

June 2007