M33, also known as the Pinwheel Galaxy for obvious reasons is a spiral galaxy in the constellation, Triangulum and is one of the prominent members of our Local Group along with the Milky Way and Andromeda galaxies.    It is about 3 million light years distant and is about 50,000 light years across; about half the size of our Milky Way.

M33 is difficult to image because of it's relatively low surface brightness and requires many more hours of exposure than one might expect as a result.  This image is comprised of over 23 hours of exposures.  Even the core of the galaxy is relatively faint as compared to other galaxies in the neighborhood.  However, this difficulty is made up for by far by the very prominent H II star forming regions evident in its spiral arms.  Those areas are the pink structures visible in this image.  Some of these regions are bright enough to have been included in Dyer's NGC catalog under their own designations separate from the NGC 598 designation assigned to the galaxy as a whole.

Back to Messier Gallery