The Hubble Space Telescope has produced a stunning new image of the globular cluster Messier 56 (also known simply as M 56 or as NGC 6779). In addition to admiring the beauty of the image, the collected data have allowed astronomers to determine that this cluster is very old, dating back to as many as 13 billion years ago, when the universe was very young.

The cluster Messier 56 is nearly 33,000 light-years from the Earth in the constellation of Lyra and was discovered by Charles Messier on January 19, 1779. At the time, however, telescopes were much more primitive than the extraordinary instruments, both ground and space based, that are available to scientists today. For this reason, most of the globular clusters discovered by Messier just looked like spheres in which it was impossible to distinguish individual stars.

Thanks to the huge technological advances of the last two centuries, today’s astronomers are not only able to see the stars in the globular cluster Messier 56 but also to understand which stars are actually in the Milky Way but since they’re between the Earth and M 56 can appear as part of the cluster. It’s important to recognize these stars because obviously to understand the features of this or other clusters the data would be “polluted” by the inclusion of “intruders”.

A typical method used to study the star clusters is their magnitude as part of what is technically called the Hertzsprung-Russell diagram. In simple words, the brightness and color of stars are compared and from this information it’s possible to understand the surface temperature due to the links between the various elements.

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Thanks to the Hertzsprung-Russell diagram, it’s possible to understand the evolution of stars and also determine their age and even their chemical composition. This is how astronomers, using observations made over time with the Hubble Space Telescope, have determined that the cluster Messier 56 is about 13 billion years old. The chemical composition of M 56 appears to be lacking in elements heavier than hydrogen and helium, a confirmation that the stars of this cluster were born when the universe was young and heavier elements hadn’t formed yet in supernovae.

M 56 is only one of many globular clusters. Their study will give us more information on the evolution of the universe, the Milky Way and hence also of our solar system.