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 elliptical Seyfert galaxy NGC 404 in Andromeda is more commonly referred to as Mirach's Ghost owing to
its very close proximity to Mirach (â-And, mag 2.06). Although it has an apparent diameter of 4.4 by 4.2 arc-minutes, it appears as a small
circular dwarf galaxy with a bright core due to the immense glare from Mirach. NGC 404 is characterized with a surface brightness of 14.6
mag/arc-min2 and which is made more difficult to observe at low powers due its 7 arc-minute distance from bright Mirach. Lying at a
distance of slightly over 10 million light-years away, it is not part of the Local
Group of Galaxies. NGC 404 was discovered by William Herschel in 1784. For a photograph of Mirach's Ghost by the Hubble Space Telescope,
click here.
Please click on the image below to display in higher resolution (1200 x 900)