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)