In age, the surface of Venus is much ________ than even the lunar ...

[karateprodigy]

In age, the surface of Venus is much ________ than even the lunar mare.
 
  Fill in the blank(s) with correct word

Question 2

If we say that a galaxy has a lookback time of 1 billion years, we mean that ________.
 
  A) it was 1 billion light-years away when the light left the galaxy
  B) it is now 1 billion light-years away
  C) its light traveled through space for 1 billion years to reach us
  D) it is 400 million years old

[tofugiraffe]

Answer to Question 1

younger

Answer to Question 2

C