•5. What is the ratio of the mass of Earth
to the mass of the moon?
(Hint: look in appendix A of the
text for these values.)
•
•Just take the ratio of masses. From table A-6, we have 6x1024 kg/7x1022 kg. 1024/1022 is 102 = 100. 6/7 is close to 1. So the answer is about 100 without needing a
calculator. Scientific notation makes it easy,
and often in astronomy we’re not concerned with super precise answers. Remember that Earth is about 100 times more massive than
the moon, not 81 times.