# Globular cluster

Also called: globular, GC.

A dense ball of hundreds of thousands of very old stars orbiting in a galaxy's halo.

Globulars are among the oldest things in the universe — about 12 billion years old. Each packs up to millions of stars into a sphere a hundred light-years across. The Milky Way has about 150 of them, swarming around its centre like bees around a hive.

In small telescopes they're fuzzy balls; with more [aperture](https://astropilot.space/glossary/aperture) and higher power the edges break up into countless pinpoint stars, and the core blazes. Omega Centauri and 47 Tucanae in the southern sky are the greatest; M 13 in Hercules is the northern showpiece.

**At the eyepiece:** Use high power on a steady night: resolving a globular into stars is all about [seeing](https://astropilot.space/glossary/seeing) and a small [exit pupil](https://astropilot.space/glossary/exit-pupil) (about 1–1.5 mm).

**Examples:** [M13](https://astropilot.space/object/M13.md), [NGC5139](https://astropilot.space/object/NGC5139.md), [M22](https://astropilot.space/object/M22.md), [NGC104](https://astropilot.space/object/NGC104.md)

**Related:** [Open cluster](https://astropilot.space/glossary/open-cluster.md), [Milky Way](https://astropilot.space/glossary/milky-way.md), [Resolution](https://astropilot.space/glossary/resolution.md), [Seeing](https://astropilot.space/glossary/seeing.md)

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