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)