Earth’s Rotation

In one day, the Earth makes a complete turn around an imaginary axis that links both Poles. This West-East rotation movement gives the impression that it is the sky that moves above us in the opposite direction. Specifically, we see the sun appearing from the East and disappearing in the West, generating a succession of days and nights.

A distinction must be made between the time it takes the Earth to make a complete turn with respect to the distant stars around its North-South axis (23 hours 56 minutes), known as sidereal day, and the time it takes the Sun to reach the same position above us. The latter is known as solar day which is divided into 24 hours. This difference between sidereal and solar day is the result of the fact that the Earth makes a shifting movement around the Sun and every day it takes 4 additional minutes to reach the same position with respect to the Sun, after reaching the same position with respect to distant stars.