Expect Venus to be similar to Earth?
(It isn�t!)
Venus only slightly closer to sun, so expect about same initial composition
Venus only slightly smaller than Earth, so expect about same heat flow
Venus atmosphere is dramatically different
Very thick CO2 atmosphere
Virtually no water in atmosphere or on surface
Venus shows relatively recent volcanic activity, but no plate tectonics
Both probably related to its slightly closer position to the sun
which caused loss of its critical water
Thick atmosphere and clouds block direct view so information from:
Orbiting radar missions(Magellan in early 90�s)
Russian landers (as in previous photo)