Author Question: During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what ... (Read 48 times)

jayhills49 · **on:** Jul 27, 2018

During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space?

A) Earth and Mars are getting closer together.
B) Mars is moving around the Sun in the opposite direction from which Earth is moving around the Sun.
C) Earth is catching up with and passing by Mars in their respective orbits.
D) Earth and Mars are on opposite sides of the Sun.

Question 2

A 20-solar-mass star will stay on the main sequence for 10 million years, yet its iron core can exist for only a

A) day. B) week. C) month. D) year. E) century.