NGC 121

Globular clusters are big balls of old stars that orbit the centers of their galaxies like satellites. This one, NGC 121, belongs to one of our neighboring galaxies, the Small Magellanic Cloud (SMC). NGC 121 is around 10 billion years old, making it the oldest cluster in its galaxy; all of the SMC's other globular clusters are 8 billion years old or younger. However, NGC 121 is still several billions of years younger than its counterparts in the Milky Way and in other nearby galaxies like the Large Magellanic Cloud.