Canis Major may be only the 43rd biggest of the 88 recognized constellations, but it does have the distinction of containing the night sky’s most luminous star, Sirius, a double star situated 8.6 light years away with a visual magnitude of -1.24. The constellation can found to the northeast of Orion from between latitudes of +60° and -90°, and from the northern hemisphere can be seen during the winter time, although best seen at about 9 PM Local Time during the month of February, when it is highest in the sky.
In terms of deep-sky objects, Canis Major is not a particularly conspicuous constellation, but it does contain one Messier object, and a number of other objects worth observing, the most notable of which are briefly explored in this list.
NGC 2359 (Thor’s Helmet)
Located about 15,000 light years away and stretching across about 30 light years, Thor’s Helmet (image above) is a reflection nebula that surrounds an extremely hot and active Wolf-Rayet star that is expected to self-destruct in a supernova explosion in the near future, astronomically speaking. Thor’s Helmet received its memorable name as its bubble shape and extending filaments makes it resemble the helmet of the god of thunder from Norse mythology. While Thor’s Helmet can be seen as a fuzzy patch in a 6-inch or smaller telescopes, a 10-inch instrument will reveal some of the arcs stretching away from the nebula’s centre.
Messier 41 (M41, NGC 2287)
The cluster is located about 4 degrees almost due south of the star Sirius, and together with Nu2 Canis Majoris forms a triangle which fits inside a single binocular field of view. The most notable aspect of M41 is that in telescopic views, the stars in the cluster are arranged in curved lines, which is not apparent on photographs.
Canis Major Dwarf Galaxy
Nonetheless, the galaxy contains about one billion stars, among which are a large number of highly evolved red giants and several globular clusters, including NGC 1851, NGC 1904, and NGC 2808. However, since the main structure of the Canis Major Dwarf galaxy is severely degraded, most investigators believe that the globular clusters and the galaxy itself represent the remains of a larger, denser structure that was tidally disrupted by the Milky Way galaxy.
NGC 2207 and IC 2163
To date, four supernova events of different types have been recorded in NGC 2207, with their detection taking place in 1975, 1999, 2003, and 2013.