Cassiopeia, mythological queen of Aethiopia, was the first constellation I learned, but it's so rich that I'm still making new connections as I explore it further. This month we'll look at two open clusters that let us "see" the depth of space. Start with 6th-magnitude NGC 129, which sits about halfway between the 2nd-magnitude stars Caph, or Beta (β) Cassiopeiae, and Navi, or Gamma (γ) Cassiopeiae, and just north of an imaginary line connecting them. The notes on my original observations, made with 7×50 binoculars, read, "compact, many stars, rivals M103 under dark skies." If conditions are good, by using 10×50 binos you may be able to spot a nice, even triangle of 9th-magnitude stars set off a bit to the south of the cluster's center. Our second target, NGC 225, glows at 7th magnitude a little more than 2° northeast of NGC 129. To me, the stars at the cluster's center look like a cup or a chalice, with fainter lights glittering within. A pleasingly symmetrical arc of 9th-magnitude stars sits just east of the cluster.
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