Author Question: Our calendar has leap years because A) there is one more sidereal day in a year than solar days. ... (Read 179 times)

Bob-Dole · **on:** Jul 27, 2018

Our calendar has leap years because

A) there is one more sidereal day in a year than solar days.
B) a tropical year is slightly more than 365 days.
C) there is a difference between a sidereal year and a tropical year.
D) the perihelion of Earth's orbit is slowly advancing.

Question 2

The most active galactic nuclei are usually found at large distances from us; relatively few nearby galaxies have active galactic nuclei. What does this imply?

A) Supermassive black holes existed only when the universe was young and no longer exist today.
B) Active galactic nuclei tend to become less active as they age.
C) Active galactic nuclei can form only at large distances from the Milky Way.
D) The jets seen in many active galactic nuclei must cause them to move far away from us.