The moonless evenings this weekend are an invitation for some deep-sky observing. Of course, spring is galaxy season. One of the finest and most famous is the Whirlpool Galaxy, otherwise known as M51.
Although it’s located in Canes Venatici, M51 is much easier to find by jumping off from Alkaid—also known as Eta (η) Ursae Majoris, the last star in the handle of the Big Dipper.
M51 is 26 million light-years from Earth—relatively nearby in cosmic terms. Chances are you’ve seen lots of impressive photos of this fine spiral specimen, but don’t let those long-exposure images set your telescopic expectations too high. At magnitude 8.1, the Whirlpool is fairly bright, yet its face-on orientation can make your observation more challenging than you may anticipate.
At nightfall during late spring, M51 is nearly overhead. Under a reasonably dark sky you can spot it with binoculars, while in a modest scope the galaxy appears as a small, round glow with a brighter centre. However, to see the spiral shape that gives the Whirlpool its name, you’ll need more aperture. I’ve detected the arms in an 6-inch, but the subtle spiral form of M51 can only really be described as obvious in a 12-inch or larger instrument.
To read about more events, check out my regular This Week’s Sky column at SkyNews.ca.