If the sun and a star cross your local celestial meridian at exactly noon today, which object will appear...?

Question

If the sun and a star cross your local celestial meridian at exactly noon today, which object will appear to cross your local celestial meridian first at exactly noon tomorrow? How much earlier will the transit take place then?

Answer 1

The true rotation period of the earth is 23 hours 56 minutes, which is the time between successive transits of a given star across the meridian. Beacuse the Earth has moved about 1 degree in its orbit around the Sun during this time, it has to rotate an extra degree on its axis to bring the Sun back to the same meridian. The time taken to rotate this extra degree is 4 minutes.

The first object to cross the meridian will therefore be the star at 11.56 a.m. with the Sun following 4 minutes later.