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Moreover, I think Venus has lost most of its hydrogen to space, so you can't even make water anymore. Hydrogen escapes the atmosphere relatively easily for Eart
by wahern 1y ago
Moreover, I think Venus has lost most of its hydrogen to space, so you can't even make water anymore. Hydrogen escapes the atmosphere relatively easily for Earth- and Venus-sized planets[1], and the vaporization of all the water and subsequent disassociation[2] of H2O allowed the hydrogen to escape into space.
[1] See https://en.wikipedia.org/wiki/Atmosphere#/media/File:Solar_system_escape_velocity_vs_surface_temperature.svg https://en.wikipedia.org/wiki/Atmosphere#/media/File:Solar_s...
[2] See https://en.wikipedia.org/wiki/Atmospheric_escape https://en.wikipedia.org/wiki/Atmospheric_escape
- saalweachter 1y agoEarth's oxygen rich atmosphere is really important here-- any free hydrogen can readily combine with the free hydrogen, decreasing the chance of any being loss.
- andrewflnr 1y agoAccording to that wiki article, the hydrogen was mostly lost in the form of water vapor. The hydrogen and oxygen in the magnetotail are in almost a perfect 2:1 ratio. At least, > Currently the main ion types being lost are O+, H+ and He+. The ratio of hydrogen to oxygen losses is around 2 (i.e. almost stoichiometric for water) indicating the ongoing loss of water. Also Earth didn't have an oxygenated atmosphere until relatively late, a couple billion years in, so I didn't know if that could be the thing that saved it.
- saalweachter 1y agoI don't have primary sources, unfortunately -- I'm recalling something I read in _Oxygen_, which I found reassuring. It said that, one of the benefits of our oxygen-rich atmosphere was that we would lose an insignificant amount of hydrogen/water over the next billion years. It's one of those things that doesn't actually matter to me in my daily life, but I still find comforting, so it's stuck with me.