M56 is a globular cluster lying about 33,000 ly from Earth in the constellation Lyra. It was discovered by Charles Messier in 1779, although, in common with other globular clusters that he discovered or catalogued, he described it as a nebula without stars because the individual stars couldn't be resolved with available telescopes. The cluster, which lies nearly in the plane of the Milky Way, is composed of stars that contain almost no elements heavier than hydrogen and helium, which is typical of stars formed early in the universe's history. Their age is estimated to be 13 billion years, about 3 times the age of our Sun.
The majority of globular clusters with this elemental composition lie along the plane of the Milky Way's halo and it is thought that they were likely captured from a satellite galaxy rather than being the oldest part of the Milky Way's globular cluster system [1].
There is a fabulous Hubble image of M 56 on [1].
I find these unusual clusters both interesting and beautiful, each having its own combination of star colours. In mid-August we had a week of clear skies and I spent some of these on clusters.
[1]
https://esahubble.org/images/potw1234a/
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