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Diurnal Motion

by

S.Beaucourt/Novapix

Reference

a-cst98-91501

Date

2010-03-17

Diurnal motion is referring to the apparent daily motion of stars around the Earth, or more precisely around the two celestial poles. It is caused by the Earth's rotation on its axis, so every star apparently moves on a circle, that is called the diurnal circle. From an observer in northern hemisphere, stars (here the constellation of Orion) are rising in the east, culminate in the south, and setting in the west.