Here's why:

* Constellations are a visual grouping: Stars in a constellation appear close together in the sky from our perspective on Earth. However, they are actually at vastly different distances from us.

* Stars form in clusters: Stars are often born in large groups called star clusters. Stars in a cluster are generally the same age because they formed from the same cloud of gas and dust.

* Stars move independently: After formation, stars within a cluster drift apart due to their own motion and gravitational interactions with other stars.

* Constellations are not clusters: While some constellations may contain stars that were once part of a star cluster, many stars within a constellation have very different origins and ages.

Example: The constellation Orion contains many stars, including Betelgeuse (a red supergiant) and Rigel (a blue supergiant). These stars have vastly different ages, even though they appear close together in the sky.