M2 is a large globular cluster located in Aquarius. Situated about 55,000 light years from earth, it contains about 150,000 stars and is about 175 light years in diameter, which translates to an average of about 1 star per 19 cubic light years. It is entertaining to think about what the night skies would look like from a planet orbiting a star in a globular cluster. A preview of a simulation done by astronomers William Harris and Jeremy Webb (
https://io9.gizmodo.com/what-the-night-sky-would-look-like-from-inside-a-globul-1589324556) gives us an idea. The highlights are that in 47 Tucanae (about 570,000 stars in a ball roughly 120 light years in diameter), an observer on a planet at the center of the cluster would see a nearest star at about 0.05 light years, 10,000 stars brighter than 1st magnitude scattered across the sky and an average sky night-time brightness about twenty times greater than on earth on a night with a full moon. The very stars themselves would be a source of light pollution! The image I took is a composite of 50 subs at 30s each and 84 subs at 15s each. The latter were used to provide a masked view of the center of the cluster. All subs were unguided and due to periodic error and wind shudder, only about 40 % of the original images were composited as described above. Seeing was poor as usual in Denver.
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