As two naked-eye open clusters within one small field of view within
southeastern Scorpius, Messier
6 (above) and even-brighter Messier 7 (below) present a special treat.
Unlike the Double Cluster in Perseus, however,
the two are completely unrelated, lying more or less just along
the same line of sight. Messier 7 (1.3 degrees and nearly 25 light years
across) lies 975 light years away, while Messier 6 (a quarter degree and 7
light years across) is farther, 1600 light years away. M 7, with an
age of 300 million years is, however, three times as old as M 6.
While seven stars in M 7 are visible to the naked eye, none has a name
other than a catalogue number. The brightest star within the confines of
M 6 is a variable class K giant, BM Sco. Just down and to the left
of M 6 is a much fainter cluster, NGC 6416, which lies 2400 light years away.
The bright star at lower right is third magnitude G Scorpii.
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