Andrew Cooper
Jul 21, 2023    Oregon Star Party, Ochoco Mts, OR (map)
25cm f/4.5 Newtonian, Holoholo @ 71x
Seeing: 7 Transparency: 6 Moon: 0%

An extremely wide scattering of stars spanning nearly the entire sky including quite a few of the stars in the northern summer sky, all of the Big Dipper asterism except Alkaid and Dubhe, while including α CrB, β Aur, δ Aqr, β Ser, ζ Leo, γ Lep, χ1 Ori, χ1 Ori, γ Mic, ζ Crt, ζ TrA, and many more.

Best observed naked eye while the central region may be sept with binoculars, the dipper itself is a striking asterism familiar to most observers in the northern sky. Scanning the sky to locate some of the other members allows an appreciation for this collection of stars.

All of these stars share a common proper motion through space and appear to have a common origin in space, the stars are probably about 300 million years old and are likely once members of the same open cluster. In some sense this makes the UMa Moving Group the closest open cluster to Earth, though the term open cluster may no longer apply as the stars have drifted apart.

Drawings, descriptions, and CCD photos are copyright Andrew Cooper unless otherwise noted, no usage without permission.

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