4 ms·

I wonder wether earth first looked similar to venus today and was made habitable by (what we today consider) extremophiles. If most of venus' atmosphere was cap

• baddox 11y ago
  One thing Venus is lacking that Earth has, which almost surely wasn't created by biological life, is a magnetic field to protect against some of the Sun's radiation.
• twic 11y ago
  Close! Earth's atmosphere was much the same as Venus's up to four billion years ago. But it seems that what made the difference was the carbonate cycle: https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cycle https://en.wikipedia.org/wiki/Carbonate%E2%80%93silicate_cyc... That article blames the difference on the temperature. Elsewhere, i've seen the presence of water oceans being implicated. Either way, i don't think life was the mechanism at that point. Life didn't really have much of an impact for another billion years or two: https://en.wikipedia.org/wiki/Great_Oxygenation_Event https://en.wikipedia.org/wiki/Great_Oxygenation_Event
  • jerf 11y ago
    Partially in response to your other post as well, I've also seen it hypothesized that the collision that produced Earth's moon stripped away most of Earth's atmosphere, the idea being that Venus' atmosphere may actually be the "normal" atmosphere for an Earth-sized planet. As usual, the core problem is just that our data set is too darned small. Is our Solar System mostly normal? Is our Solar System a bizarre, billions-to-one odds freak case? We don't really know.