Download A Short History of Venus

A Short History of Venus
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Venus accreted from asteroids and planetoids ~ 4.6 billion years ago, as did
Earth, and the other planets.
Venus formed with about the same mixture of elements as Earth.
The planet melted and differentiated into a metal-rich core and a lighter
mantle.
A secondary atmosphere was outgassed from volcanic activity, containing
H2O, CO2, SO2 (sulfur dioxide), CH4 (methane) and nitrogen.
Possibly, a catastrophic impact occurred early in Venusian history, which
“flipped” the planet, and drastically slowed its rotation (not proven).
Venus underwent a runaway greenhouse effect – due to the presence of
“greenhouse” gases. As the temperature increased, all of the existing water
became vapor, circulated high into the atmosphere. This vapor was split apart
by solar UV radiation, the hydrogen released was lost to the planet.
Without a hydrological cycle, all of the outgassed CO2 remained in the
atmosphere, resulting in the dense, hot atmosphere seen today.
Data obtained by radar-mapping satellites has shown that extensive volcanic
and tectonic activity has reshaped the Venusian surface. However, for
reasons not understood, Venus does not experience Earth-like plate
tectonics.
A major “repaving” appears to have occurred between 0.5 – 1.0 billion years
ago. Venus most likely possesses the youngest surface amongst the
terrestrial planets.
Although not yet demonstrated, Venus most likely remains volcanically active.