Earth, then Mars…Venus Next in Line for "Giant Impact" Explanation
Big news today about Mars’ peculiar north-south terrain divide having been caused by the impact of a Moon-size object shortly after the planet formed. Since there is also strong evidence for Earth having undergone a similar impact, with a Mars-size planetoid, thereby forming our Moon, it would be odd to imagine that no such catastrophe ever occurred to Venus.
After all there’s lots still to explain about “Earth’s Twin”: a very slow retrograde rotation, an incredibly massive atmosphere and a relatively young (<500 million years) surface. To me, the whole setting cries out loud for an “impact” explanation, rather than the classic “it’s warm because of the CO2!” theory that says nothing about all the other peculiarities (and it’s not exactly necessary…).