Why doesn't thermal energy just escape into space? (don't say gravity)?

Answer 1

It escapes into space all the time. There is a thermal gradient from the surface of the earth going out to space. The other answers are correct in that the reason the earth does not freeze is there is an equilibrium between the energy lost and the energy gained (It is not just solar)

Answer 2

It does, all the time! If the sun were to go out right now, within an hour the atmosphere would liquefy an the whole planet would become cryogenically cold!

The reason the earh isn't so cold is that the heat loss due to radiation into space is matched by the influx of radiant energy we get from the sun.

The atmosphere doesn't insulate the planet, it just redistributes the thermal energy on the planet. So, really it's more of a conveyor to bring the warmth from the equator out towards the poles.

Answer 3

The atmosphere acts like an insulator. A lot of thermal energy does escape but the sun keeps adding more.

Answer 4

Steve is right. It does escape into space mainly by radiation. There is some conduction loss and some convection loss to the higher atmosphere, but mostly by radiation. Interestingly, the Earth is warmed by internal energy from its core, due to nuclear decay. And the atmosphere does help to keep the heat trapped and stop us becoming too cold. Too hot is not good either.

Answer 5

Thermal energy is kinetic energy of the atoms and molecules and so it's not a "fluid" which can just escape up into space like a gas