Thermos Bottles and the Sun?

Question

If you put hot water in a vacuum / thermos bottle, it will stay hot due to the vacuum insulating it from the outside air.
There is a 93 million mile vacuum between us and the sun, yet when I go outside, it feels hot.
Why?

Answer 1

a thermos bottle works on three principles of heat transfer to keep the contents from changing temperatures.
Conduction - blocked by the vacuum and other low heat conducting materials.
Convection - blocked by keeping the contents isolated from other materials
Radiation - blocked by using a reflective coating inside the bottle.

The radiation from the sun transfers energy (heat) to the earth because it is not blocked by a filter or mirror.

Answer 2

In your thermos bottle analogy the walls of the bottle are the sun's surface and the earth's atmosphere, separated by a vacuum.

The sun's surface is *hot* and emits radiant heat which travels just fine through a vacuum.
The earth's atmosphere absorbs and retains heat quite well. So, the earth is warmed by the sun with no problem.

To really make the thermos bottle analogy, the vacuum in your bottle would have to contain a potent infrared heat source directed on the inner wall through the vacuum. In that case the water contained inside would definitely heat up!

Answer 3

By radiant heat. A vacuum only prevents conduction and convection, not radiation. Radiation is not just atomic radiation; it is also light and heat and radio waves. Thermos bottles protect against radiant heat by hading the inside of the vacuum jacket silvered, like a mirror.

Answer 4

This is a great question! I can't answer it any better than the others have just wanted to complement you on your question!