The fact that the Earth-Moon system orbits the Sun (covering 30° per month) in a clockwise direction viewed from the celestial north pole while the Moon orbits Earth, also in a clockwise direction, means that the time between successive full moons, the synodic month, compared to one lunar orbital (sidereal) period is:
A)about twice as long.
B)about 2 days longer.
C)about 2 days shorter.
D)about 2 weeks longer.

Question

Quizplus · Accepted Answer

The synodic month is about 2 days longer than the sidereal month because as the Moon orbits Earth, both the Earth and Moon are also moving around the Sun, requiring the Moon to travel a bit more than one full orbit to reach the same phase.

The Fact That the Earth-Moon System Orbits the Sun (Covering