The time for the Moon to orbit Earth, relative to the stars is ...

[vinney12]

The time for the Moon to orbit Earth, relative to the stars is
 
  A) 23 hours, 56 minutes.
  B) about 7 days.
  C) 27.3 days.
  D) 29.5 days.
  E) 18 years, 11.3 days.

Question 2

Doppler shifted hydrogen absorption lines are seen in the spectrum of a star. The hydrogen line at 656.28 nm is seen to be shifted to 656.08 nm. The star is moving at which fraction of the speed of light?
 
  A) about 0.000003 (3  106 ) B) about 0.0003 (3 104 )
  C) about 0.2 D) about 0.03 (3  102 )

[TheNamesImani]

Answer to Question 1

C

Answer to Question 2

B