(See description below)
Messier 5 Globular Star Cluster
sparkling jumble is Messier 5—a globular cluster consisting of hundreds
of thousands of stars bound together by their collective gravity.
The cluster is about 165 light-years in diameter. (The
image here spans 20 light-years.)
Messier 5 is no normal globular cluster. At 13 billion years old it is
incredibly old, dating back to close to the beginning of the Universe,
which is some 13.8 billion years of age. It is also one of the biggest
clusters known, and at only 24 500 light-years away, it is no wonder
that Messier 5 is a popular site for astronomers to train their
5 also presents a puzzle. Stars in globular clusters grow old and wise
together. So Messier 5 should, by now, consist of old, low-mass red
giants and other ancient stars. But it is actually teeming with young
blue stars known as blue stragglers. These incongruous stars spring to life when stars collide, or rip material from one another.