4 ms·

It's not that the water "blew away" in the solar wind, it's that the atmosphere did, taking the water vapor in the atmosphere with it. This is a very gradual pr

by eloff 4y ago

It's not that the water "blew away" in the solar wind, it's that the atmosphere did, taking the water vapor in the atmosphere with it. This is a very gradual process, which would happen on Earth too, if not for the magnetic field. I don't know that the collision with the moon is the secret here or not. I think it's complex.

sneak 4y ago
Neither Venus nor Mercury have substantial magnetic fields presently (compared to Earth). I don’t know enough to know if that supports the GP’s conclusion or not, but it may.
- throwaway5752 4y ago
  These are pretty well researched, observed, and understood subjects. https://en.wikipedia.org/wiki/Atmosphere_of_Venus https://en.wikipedia.org/wiki/Atmosphere_of_Venus explains it quite well, particular https://en.wikipedia.org/wiki/Atmosphere_of_Venus#Induced_magnetosphere https://en.wikipedia.org/wiki/Atmosphere_of_Venus#Induced_ma... which explains how Venus is currently losing its atmosphere in the way described above. And https://en.wikipedia.org/wiki/Atmosphere_of_Mercury https://en.wikipedia.org/wiki/Atmosphere_of_Mercury: "The Mercurian exosphere consists of a variety of species originating either from the Solar wind or from the planetary crust [...] This corresponds to a surface pressure of less than 10^-14 bar (1 nPa)" which is about 1% of what is considered "ultra-high vacuum" (https://en.wikipedia.org/wiki/Orders_of_magnitude_(pressure) https://en.wikipedia.org/wiki/Orders_of_magnitude_(pressure)) Mercury has no magnetic field, and no meaningful atmosphere like we'd understand it. Venus has a minimal magnetic field, and is covered in hot dense CO2 layer because the solar wind blew away all the hydrogen and continues to blow away the atmosphere. The Earth has a much stronger magnetic field that has protected our oxidized hydrogen, and good evidence points to the giant impact hypothesis.

by eloff 4y ago

sneak 4y ago

Neither Venus nor Mercury have substantial magnetic fields presently (compared to Earth). I don’t know enough to know if that supports the GP’s conclusion or not, but it may.

throwaway5752 4y ago
These are pretty well researched, observed, and understood subjects. https://en.wikipedia.org/wiki/Atmosphere_of_Venus https://en.wikipedia.org/wiki/Atmosphere_of_Venus explains it quite well, particular https://en.wikipedia.org/wiki/Atmosphere_of_Venus#Induced_magnetosphere https://en.wikipedia.org/wiki/Atmosphere_of_Venus#Induced_ma... which explains how Venus is currently losing its atmosphere in the way described above. And https://en.wikipedia.org/wiki/Atmosphere_of_Mercury https://en.wikipedia.org/wiki/Atmosphere_of_Mercury: "The Mercurian exosphere consists of a variety of species originating either from the Solar wind or from the planetary crust [...] This corresponds to a surface pressure of less than 10^-14 bar (1 nPa)" which is about 1% of what is considered "ultra-high vacuum" (https://en.wikipedia.org/wiki/Orders_of_magnitude_(pressure) https://en.wikipedia.org/wiki/Orders_of_magnitude_(pressure)) Mercury has no magnetic field, and no meaningful atmosphere like we'd understand it. Venus has a minimal magnetic field, and is covered in hot dense CO2 layer because the solar wind blew away all the hydrogen and continues to blow away the atmosphere. The Earth has a much stronger magnetic field that has protected our oxidized hydrogen, and good evidence points to the giant impact hypothesis.