Globular clusters of stars such as Messier 9, seen here in a recent image from the Hubble Space Telescope, are twice as old as our Sun, and are made up of stars that are among the oldest in our galaxy.
About 8 Billion years old, the more than 250,000 stars of Messier 9 are enriched with far fewer heavier elements than the Sun. Elements crucial to life on Earth, like oxygen and carbon, and the iron at Earth's core are rare in Messier 9.
Spotted with color, this image shows the wide range of temperatures in the stars of Messier 9, with redder stars being cooler, and bluer stars hotter.
(Credit: NASA and ESA)