What’s a globular cluster? The Milky Way has about 150
A globular cluster is a spherical collection of stars orbiting in the halo of spiral galaxies. Our own Milky Way galaxy has over 150 globular clusters. The post What’s a globular cluster? The Milky Way has about 150 first appeared on EarthSky .
A globular cluster is a dense, symmetrical group of stars that orbit around the center of a galaxy. Our Milky Way galaxy is home to about 150 such clusters, with some containing millions of stars. These clusters are among the oldest objects in the universe, with ages ranging from 11 to 13 billion years, making them older than the galaxy itself.
Globular clusters are composed of ancient Population II stars, which have very low metal content compared to other stars. This means they are primarily made up of hydrogen and helium, the elements that existed in the early universe before the formation of heavier elements in stars. While globular clusters contain hundreds of thousands to millions of stars, they are densely packed in the halo of the galaxy and do not orbit within the disk.
In contrast, open star clusters, which are less dense and more loosely arranged, typically have fewer stars and orbit within the galactic disk.
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