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Space Forum / Space Science / August 2008Solar Wind and Venus' Atmosphere
I have seen several shows on the science channel (among others) that have stated that the Earth's atmosphere would be eroded -- to the extent seen on Mars -- if the Earth did not have a strong magnetosphere. This leaves me with the question -- conveniently ignored by those same programs -- Venus has no magnetosphere, so why has its atmosphere not even more sparse than Mars? After all the solar wind on Venus should be (hundreds?) of times stronger on Venus than Mars. So it seems somewhat disingenuous of the writers and producers not explain Venus when they are comparing Mars to Earth. Perhaps the only thing that the solar wind has been able to erode from Venus' atmosphere is its hydrogen and oxygen. -- Matt Hickman Since Venus appears to have a more molten interior than Earth (perhaps due to constant gravitational pressure -- as opposed to Earth, which had its early, cataclysmic lunar-formational event) it may be replenishing its carbon dioxide, etc., at a rate much higher than its solar erosion quotient. If we knew how much atmosphere Mercury started with, at the time of solar ignition, then rates of atmospheric erosion might be pinned down more precisely. However, as it is, Earth seems to be a special case with its plasma tail getting hooked around by the moon and its vast open seas. As for Mars, the mysteries still appear open-ended. If there actually was a thicker atmosphere at some point, something must have happened to it. From looking at features like the Tharsis vents, and the Hellas impact, more possibly was involved than mere sublimation and solar winds... > I have seen several shows on the science channel (among others) that > have stated that the Earth's atmosphere would be eroded -- to the [quoted text clipped - 13 lines] > -- > Matt Hickman > Since Venus appears to have a more molten interior than Earth (perhaps > due to constant gravitational pressure -- as opposed to Earth, which > had its early, cataclysmic lunar-formational event) it may be > replenishing its carbon dioxide, etc., at a rate much higher than its > solar erosion quotient. Thanks. With a more molten interior than Earth, one would expect that Venus would also have experienced an iron catastrophe like Earth apparently did and therefore have an iron core. The nearly non- existent magnetosphere can be blamed on the slowness of the planetary rotation? Or is current thinking that Venus does not have an iron core? > > Since Venus appears to have a more molten interior than Earth (perhaps > > due to constant gravitational pressure -- as opposed to Earth, which [quoted text clipped - 8 lines] > planetary rotation? Or is current thinking that Venus does not have > an iron core? There's most likely a core of iron, or perhaps even along with its fair share of thorium. ~ Brad Guth Brad_Guth Brad.Guth BradGuth > I have seen several shows on the science channel (among others) that > have stated that the Earth's atmosphere would be eroded -- to the [quoted text clipped - 13 lines] > -- > Matt Hickman Venus is not as old as Earth, and as such it's still extremely geothermal and unavoidably venting S8 and Co2 like crazy, and obviously spewing muds and lava along with releasing some of its h2o. Perhaps Venus once had a moon of roughly 7.35e22 kg. ~ Brad Guth Brad_Guth Brad.Guth BradGuth |
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