The Whirlpool Galaxy (M51) and its smaller companion NGC 5195 are excellent targets tonight before the Moon rises.
Two hours after sunset, the sky is dark and the constellation Canes Venatici is high in the west, nestled beneath the curve of Ursa Major’s long tail, which also creates the handle of the Big Dipper asterism.Â
Located in northern Canes Venatici is M51, famously known as the Whirlpool Galaxy. It’s easy to find just 3.5° southwest of magnitude 1.9 Alkaid, also cataloged as Eta (η) Ursae Majoris, the star at the very end of the Big Dipper’s handle.
The Whirlpool is a face-on spiral galaxy that shows off both its bright nucleus and winding arms. Shining at magnitude 8.4, it’s a bright galaxy and any small scope will capture it as a circular glow that brightens toward the center, but larger telescopes (6 inches or more) will, as always, reveal more detail — in this case, resolving its individual spiral arms from some 31 million light-years away.Â
You’ll also notice a smaller, more compact bright object just north of the main galaxy’s glow. This is M51’s companion galaxy, magnitude 9.6 NGC 5195. Astronomers have determined that NGC 5195 appears to be passing behind M51 from our point of view; the two galaxies have been interacting for hundreds of millions of years. This has enhanced the spiral structure of the Whirlpool, contributing to its standout appearance in our sky.Â
Sunrise: 5:31 A.M.
Sunset: 8:31 P.M.
Moonrise: —
Moonset: 9:27 A.M.
Moon Phase: Waning gibbous (81%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. local time from the same location.
For a look ahead at more upcoming sky events, check out our full Sky This Week column.Â
