Here's why:

* Earth's Rotation: The Earth spins on its axis, completing one rotation every 24 hours. This causes the stars to appear to move across the sky from east to west.

* Earth's Orbit: As the Earth revolves around the Sun, our perspective of the stars changes throughout the year. This means different constellations are visible at different times of the year.

Think of it like this: Imagine you're on a carousel. As the carousel spins, the objects around you seem to move, even though you're just rotating. Similarly, the Earth's rotation makes the stars appear to move.

However, there's a twist!

While stars and constellations *do* shift positions over time, they do so in a predictable way. This is because the stars are incredibly far away, and their movements are very slow.

So, while you won't see the same stars in exactly the same spot every night, their general patterns and the constellations they form will be consistent throughout the year.