Just as the Sun moves through the sky, the stars do too!
This is all due to the counterclockwise rotation of the Earth. Think of the Earth as a 360 degree circle and divide that by the 24 hours that it takes the Earth to make a single rotation. The result is a movement of 15 degrees per hour in a huge arc across the sky from East to West.
Hold out your hand at arm’s length and spread out your index finger and little finger as far as you can (like a hook ‘em). That is about 15 degrees and 1 hour of star travel in the sky!
Next compare the image below to the one at the top of this page, the first one is a 1 hour exposure and the second one is a 20 minute exposure. You can observe the difference in the length of the star trails, that’s the rotation of the Earth!
Go outside and align a star to a landmark nearby such as a post or tower.
Observe how the star slowly moves over time.
Follow the link below to learn more about measuring distance in the sky yourself!