Why does the night sky look a bit different after 100 years?

Question

I am using Heavens Above interactive Skychart and noticed that if you move the year by 100 year increments, the night sky changes, but not so much. What causes this?

In: Planetary Science

Answer 1

The stars are all orbiting around the galaxy at different speeds and different orbits. So they are also moving relative to us. Because the distances are so vast, we don’t notice it over short time scales. It takes hundreds or thousands of years to make it apparent to the naked eye.