M41: A faint star cluster near bright Sirius
Find star cluster M41
Do you want to see a star cluster? Then just look for nighttime’s brightest star, Sirius, in the constellation Canis Major the Greater Dog. A lovely star cluster – called Messier 41 or M41 – lies near Sirius. If you can’t see the star cluster, it’s probably because your sky isn’t dark enough. So try aiming your binoculars at bright Sirius. You might glimpse the little star cluster in the same binocular field.
Sirius is easy to spot. It’s bright, brighter than any other star you’ll see in the evening sky now. You can be sure you’re looking at Sirius if Orion’s Belt – three stars in a short, straight row in the constellation Orion the Hunter – are pointing to it.
M41 lies about 4 degrees south of Sirius. Most stars look like pinpoints. But the cluster looks like a fuzzy spot, unlike a typical star. It shines at magnitude 4.5 – within the limit of vision to the unaided eye – so some people do see M41 with the eye alone in a dark sky. Individuals with particularly good vision have likely spotted it throughout human history.
Sometime before 1654, the early astronomer Giovanni Battista Hodierna noticed M41 and placed it in his catalog of comets and other celestial objects. In the late 1700s, M41 was one of the objects that astronomer Charles Messier (1730-1817) thought could be mistaken for a comet. He was looking for comets, and so compiled a list of these objects to avoid in his now-famous Messier Catalog.
Messier 41 is an open cluster
M41 is an open star cluster made of sibling stars still moving together through space. They are loose collections of stars, located in the flat disk of our Milky Way galaxy, born from a single cloud of gas and dust in space. They are very beautiful when viewed through binoculars or a small telescope.
Like most open star clusters of its type, M41 is relatively young, probably between 190 and 240 million years old. By contrast, our sun is about 4 1/2 billion years old.
M41 lies 2,300 light years away. The cluster – whose true diameter in space covers about 25 light-years – contains about 100 stars including several red giants.
At mid-northern latitudes, Sirius and M41 stay out until roughly 4 a.m. local time at this time of year.
So enjoy Orion, the star Sirius and M41 on these January and February evenings. And by the way, there are over 100 of the so-called Messier objects or M-objects to find and enjoy. Today’s amateur astronomers consider them among the most prized objects to view through binoculars and small telescopes. Here’s a list of M-objects. Advanced amateurs can observe them all and can earn a Messier certificate from the Astronomical League.
Bottom line: No matter where you are on Earth, look for the sky’s brightest star, Sirius, in the months of January, February and March. If your sky is dark enough, notice the faint fuzzy object near the bright star Sirius. This object is called M41, and it’s a distant cluster of stars.