Question

Do all the stars in the sky move? Explain.

Answer 1

Hint: Recall do the stars really move with respect to earth? We know that the earth rotates from west to east with respect to the celestial sphere. Consider the star located on the celestial pole.

Complete step by step answer:
To answer this question we need to understand do the stars really move in the sky with respect to the earth? No! The stars do not move in the sky with respect to the earth but they appear to move in the sky with respect to a fixed point on the earth. The earth moves from west to east on the celestial equator. Therefore, the star fixed at a certain point on the celestial sphere appears to move from east to west in the sky when the earth moves from west to east.

Now, suppose we are standing on the poles and the star is exactly at our zenith. The rotation of the earth will affect the star’s apparent motion in the sky because the point of the poles remains stationary. Therefore, we can say that the stars directly overhead at the poles do not move in the sky. The bright star Polaris is currently at from the north celestial pole and does not move in the sky.

Additional Information:
We briefly explain some of the astronomical terms used to answer this type of question.
Zenith: The point directly overhead in the sky is known as zenith.
Celestial poles: We know that the earth has two poles: South Pole and North Pole. To locate the position of the astronomical objects in the sky, astronomers use the term celestial poles. The celestial pole is the extension of the earth’s poles on the celestial sphere. If a certain star is located at the zenith of the South Pole then it’s location on the celestial sphere is given as a star on the celestial south pole.

Note:
The star Polaris is the only bright star that does not move in the bright sky. Therefore, in early days, sailors used the location of Polaris to locate the south pole of the earth. The stars are stationary with respect to earth but they also move in the Milky Way.