Globular star clusters, ancient spherical groupings of several thousand stars, roam the halo of our Milky Way Galaxy. These globular star clusters are gravitationally bound and older than the stars of the galactic disk. Incredibly, measurements of globular cluster ages appear to be even older than the stars in the Universe. Accurate cluster distance determinations gice us a rung on the astronomical distance ladder. Pictured above is the globular star cluster NGC 6934 and it lies about 5,000 light-years away in the constellation Delphinus. Because of this large distance, we know that this image from Hubble's Advanced Camera for Surveys spans about 50 light-years. Such cluster stars are estimated to be some 10 billion years old.
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