Every other stellar object will appear to 'move' in our sky, relative to the sun. This is due to the earth's orbit, and is linked into how sidereal time works. Sidereal time is used by astronomers to determine where a certain heavenly body will appear in our sky at any given time.

Do we use sidereal or solar day?

A solar day is the time it takes for the Earth to rotate about its axis so that the Sun appears in the same position in the sky. The sidereal day is ~4 minutes shorter than the solar day. The sidereal day is the time it takes for the Earth to complete one rotation about its axis with respect to the 'fixed' stars.

Do astronomers use sidereal time?

Sidereal time (/saɪˈdɪəriəl/ sy-DEER-ee-əl) is a timekeeping system that astronomers use to locate celestial objects. Using sidereal time, it is possible to easily point a telescope to the proper coordinates in the night sky.