Star clusters are groups of stars formed out of the same molecular cloud at birth.
The sun has been around for 4.5 billion years, and has orbited the center of the galaxy about 20 times since then. Star clusters rarely survive for that long. I know of no evidence from studies of nearby stars that would indicate they are part of a cluster, instead, they seem to be simply moving in roughly the same orbit as the sun around the galactic center, but within in a few billion years, a whole new group of nearby travelers will swim into view. It seems to be a constantly changing population, much like the traffic on a highway. Return to the Ask the Space Scientist main page.