proper motion

Proper motion refers to the apparent movement of a star or other celestial object across the sky, as seen from Earth. This motion is due to the star's genuine velocity through space, often measured in arcseconds per year. Unlike the more familiar motion of stars resulting from Earth's rotation, proper motion reveals how stars are moving relative to our solar system. While most stars move slowly across the sky, some can be relatively fast, indicating they may be closer to us. Proper motion helps astronomers understand the dynamics of our galaxy and the positions of stars.