Galaxies are perhaps one of the most attractive deep-sky objects to observe and photograph. They represent massive collections of dust, gas and countless billions of stars and are best described as islands of space matter across the universe. They are characterized as being either spiral or elliptical in nature and usually have a bright central core. Equally stunning to observe (with large-aperture telescopes) and image are galaxy clusters which represent collections of gravitationally-bound groups of galaxies whose members number from tens to thousands and which are classified on the basis of their richness (ie. number of galaxy members), shape (spherical, flat or irregular) and content (spiral or elliptical). Charles Messier's list of deep-sky celestial gems includes approximately forty bright and large galaxies.

Our own galaxy, the Milky Way, represents a galaxy within the Local Group (of Galaxies) numbering 30 galaxies in total, five million light years in diameter and which is moving in unison towards the constellation of Virgo. Other prominent galaxies within the Local Group include Andromeda (150,000 light-years in diameter), Triangulum (40,000 light-years in diameter) and the Large and Small Magellanic Clouds (30,000 and 20,000 light-years in diameter respectively). The center of the Local Group is believed to lie between the Milky Way and the Andromeda Galaxy. The richest member of our Local Group is the Virgo Cluster which is believed to contain approximately 2500 galaxies mostly elliptical in nature.

Note: The Pinwheel Galaxy in Ursa Major is one of the most stunning examples of a face-on galaxy with impressively resolved and stunning spiral arms. Lying at a distance of 27 million light-years away, M101 has an apparent diameter which approaches that of the full moon and representing a span of 210,000 light-years across. It is fairly bright (mag 8.31), generally circular and with a bright core but a fairly dim surface brightness of only 15.3 mag/arcmin². The assymetry observed during extended photography reveals its misplaced core and which prompted Halton Arp to include this galaxy as "Arp 26" in his compilation of peculiar galaxies and under the sub-category of "Spiral with One Heavy Arm".

The Pinwheel Galaxy is the dominant member of the M101 group of galaxies and which includes M51 (mag 8.5), M63 (mag 9.3), NGC 5195 (mag 10.5), NGC 5585 (mag 11.2) and another ten smaller and dimmer member galaxies. M101 has been host to three supernovae (SN 1909A, mag 12.1; SN 1951H, mag 17.5; and SN 1970G, mag 11.5). Various portions of the outer spiral arms have NGC numbers of their own and include NGC 5547, NGC 5549-5451, NGC 5453, NGC 5355, NGC 5359, NGC 5461-5462 and NGC 5471. This galaxy was discovered by Pierre Mechain in 1781 who described it as a "Nebula without star, very obscure & pretty large" and which was added by Messier to his famous catalog of fuzzy objects.