Page 71 - Astronomy - October 2017 USA

3. PTOLEMY’S CLUSTER
Open cluster M7 in the constellation
Scorpius the Scorpion is the eighth-
brightest such object in the sky.
Shining at magnitude 3.3, it’s an easy
catch with naked eyes from a dark site.
This object lies about 980 light-years
away. It carries the common name
“Ptolemy’s Cluster,” although when
that philosopher observed it, he
classified it a nebula. • Dan Crowson
4. SUNBEAMS
Crepuscular rays form when sunlight
streams through breaks in distant
clouds, creating shafts of alternating
sunlit and shadowed air. If you trace
all the rays back to their origin, you’ll
arrive at the Sun. The word crepuscular
comes from the Latin for “twilight,”
named that because we see them most
often at sunset. • Jared Bowens

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