The stars appear to remain in fixed positions in the sky, primarily due to their great distances from Earth. Here’s a more detailed explanation:
Distance and Perspective: Stars are incredibly far from Earth. Even though they are moving in space, the distances involved are so vast that any changes in position are imperceptible to the naked eye over short periods, such as a year. The apparent positions of stars are stable because these minuscule shifts due to their motion aren’t noticeable without precise instruments.
Proper Motion: Every star moves through the galaxy, but this motion, known as proper motion, is incredibly slow from our vantage point. For example, a star might move only a fraction of a degree over centuries. Only a few stars with relatively high proper motion, such as Barnard’s Star, show noticeable change over human lifetimes and even those changes require careful observation over many years.
Earth’s Orbit: As Earth orbits the Sun, stars rise and set at different times, causing seasonal sky changes, and the stars visible at night vary with the seasons. However, the constellations themselves don’t change their layouts—Orion looks the same year after year. This annual shift is caused by Earth’s movement around the Sun, not by any change in the stars’ positions.
Precession: Over the very long term (i.e., thousands of years), the orientation of Earth’s axis changes in a process known as precession, which slowly alters the apparent position of stars and constellations in relation to Earth. However, these changes are so gradual that they aren’t noticeable on a yearly basis.
In essence, while stars and the constellations they form do have motion and their positions relative to Earth do change, the scale of these changes is so large that they become apparent only over long timeframes, far exceeding a single year.