Explanation:
Globular
star clusters roam the halo of our Milky Way Galaxy.
Gravitationally
bound, these spherical groupings of
typically several hundred thousand stars are ancient,
older than the stars of the galactic disk.
In fact, measurements of globular cluster
ages constrain
the age of the Universe (it must be older than the stars in it!) and
accurate cluster distance determinations
provide a rung on the astronomical distance ladder.
Globular star cluster
NGC 6934
itself lies about 50,000 light-years away in the constellation
Delphinus.
At that distance,
this sharp
image from Hubble's Advanced Camera for Surveys spans
about 50 light-years.
The cluster stars are estimated to be some 10
billion years old.
