astrophysics, geology, photosynthesis, physics

Evaporating Earth

It is usually assumed, that a lot of space debris lands on our planet each day and enlarges it. Well, it does, but a lot more goes up into the interplanetary space, never to come back.

It does rain on our planet, but the evaporation is more significant, Earth is smaller every day! For about 4 to 5 thousand tons each day, only a small percentage comes down as meteorites.

The vast majority of the escaping mass is hydrogen, at the rate of 50 kilograms per second, due to the escape velocity many hydrogen molecules have, because of their small mass and the thermodynamics of the gases.

This unfortunately also means that almost half a ton of water is lost every second. Since the days of dinosaurs this amounts to a million cubic kilometers of water. Maybe it doesn’t sound much, but otherwise the ocean would be several meters higher. The Earth is slowly drying.

The main driver of this process is photosynthesis, which actually breaks water molecules. A fraction of the hydrogen  produced escapes, the oxygen oxidizes something else and remains here.