# Open cluster

Also called: galactic cluster, star cluster.

A loose group of tens to thousands of young stars born together from the same cloud.

Open clusters are the stellar families of the [milky way](https://astropilot.space/glossary/milky-way)'s disk: stars that formed together a few million to a few hundred million years ago, slowly drifting apart. Many are bright enough for binoculars — the Pleiades and the Beehive are naked-eye clusters.

They look best at low to medium power, framed with dark sky around them so the cluster stands out from the background stars.

**At the eyepiece:** Don't overmagnify: a cluster that fills the whole field just looks like a rich star field. Aim for the cluster to fill about half the view.

**Examples:** [M45](https://astropilot.space/object/M45.md), [M44](https://astropilot.space/object/M44.md), [NGC869](https://astropilot.space/object/NGC869.md), [M11](https://astropilot.space/object/M11.md)

**Related:** [Globular cluster](https://astropilot.space/glossary/globular-cluster.md), [Asterism](https://astropilot.space/glossary/asterism.md), [True field of view](https://astropilot.space/glossary/true-field.md), [Cluster + nebula](https://astropilot.space/glossary/cluster-nebula.md)

From the AstroPilot astronomy glossary: https://astropilot.space/glossary/open-cluster