A sidereal day is defined as ________.
A)24 hours in a day
B)the time for one complete revolution of the earth relative to the celestial reference
C)the time between periods when the sun is at the exact same height in the sky,for example,noon
D)24 hours at Greenwich,England

Question

Quizplus · Accepted Answer

A sidereal day is the time for one complete rotation of the Earth relative to the celestial reference, which is approximately 23 hours, 56 minutes, and 4 seconds. This is different from a solar day (choice C), which is the time between two successive crossings of the Sun over the local meridian, and is approximately 24 hours. Choice A is simply the length of a solar day, and choice D is a specific reference point for measuring time (Greenwich Mean Time).

A Sidereal Day Is Defined as ________