Westerlund 2 is a 2-million-year-old star cluster of 3,000 massive, hot, and bright stars in the stellar nursery Gum 29

Image Credit: NASA, ESA, A. Nota (ESA/STScI), and the Westerlund 2 Science Team

This Hubble image shows Omega Centauri, a globular star cluster 15,790 light-years from Earth

Image Credit: NASA/ESA/Hubble  SM4 ERO Team

Hubble’s WFC3 captured Liller 1, a dense star cluster 30,000 light-years away, with stars over 11 billion years old

Image Credit: ESA/Hubble & NASA,  F. Ferraro

Trumpler 14, an open cluster 8,000 light-years away, hosts some of the galaxy’s most massive, luminous stars

Image Credit: NASA, ESA, and J. Maíz Apellániz (Institute of Astrophysics of Andalusia, Spain)

This Hubble image shows part of the loosely bound open cluster Caldwell 71

Image Credit: NASA, ESA, and T. von Hippel (Embry-Riddle Aeronautical University)

Terzan 4, a globular cluster in Scorpius, contains thousands of stars—hot, bright blue ones at the center and cooler, older red ones on the edges

Image Credit: ESA/Hubble & NASA, R. Cohen