Stars, of course, do move. It’s just that the distances are so great that it’s very difficult to tell. But astronomers have been studying their position for thousands of years. Tracking the position and movements of the stars is known as astrometry.

A given pattern of stars may move across the sky and turn sideways or even upside-down, but it won't grow larger or smaller, or change its shape in any other way. The permanence of the stellar patterns encourages us to mentally connect the dots to make pictures, called constellations.