•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)