M33

From South Dublin Astronomical Society

M33
Type	Spiral galaxy
NGC	NGC 598
Constellation	Triangulum
Right Ascension	1h 33.9m
Declination	+30° 39’
Magnitude	5.7
Size	73 x 45 arc min.
Image:M33 messier image.jpg

M33 is found roughly one-third of the way along a line joining Alpha Trianguli and Beta Andromedae. It’s light is spread out over a large patch of sky about one degree in diameter and this low surface brightness makes it difficult to spot. You should be able to glimpse it’s ghostly glow, given good clear conditions, with the naked eye or low-power binoculars though. At a distance of 2·5 million light years it is a slightly more remote member of the Local Group of galaxies than M31. It is about half the size of the Milky Way and long exposure photographs bring out its loose spiral structure with the “arms” knotted with bright star-forming regions. All told, the Local Group has just over 30 members and mostly consists of a rag-tag assortment of dwarf irregular and elliptical galaxies. M33 ranks as the third largest member after M31 and our own Milky Way.