M88, mag. +9.6, is a fine spiral galaxy located in Coma Berenices that's a member of the Virgo cluster of galaxies. It has a reasonably high surface brightness, which is partly due to its favourable inclination of 30 degrees. As a result, it's a nice small telescope object that appears somewhat like a much smaller and fainter version of M31, the spectacular Andromeda Galaxy.
M88 is one of the brightest Seyfert galaxies in the sky. These types of galaxies have very active quasar like nuclei and are strong emitters of electromagnetic radiation with highly ionised spectral emission lines present. They are named after 20th century American astronomer Carl Seyfert who first identified them. Galaxies M51, M66, M77, M81, M87 and M106 also belong to this class of object.
M88 was one of the eight Virgo cluster galaxies discovered by Messier on March 18, 1781, his most productive night. Messier's description of M88 was of a "nebula without star between two small stars and one star of the sixth magnitude, which appear at the same time as the nebula in the field of the telescope". He also remarked that it was similar in appearance to M58. William Parsons the 3rd Earl of Rosse was the first to recognise the spiral shape and listed it as one of 14 "spiral nebulae" discovered to 1850.
As with some of the Virgo galaxies, locating M88 can be challenging as there are no bright stars in the vicinity. The galaxy is positioned about a degree north of the Coma Berenices-Virgo constellation boundary. This region of sky can be found midway between stars Denebola (β Leo - mag. +2.1) and Vindemiatrix (ε Vir - mag. +2.8). Tenth magnitude barred spiral galaxy, M91, is located just east of M88.
The best time of year to look for the Virgo galaxies is during the months of March, April and May.
M88 is bright enough to be seen with 7x50 or 10x50 binoculars on dark nights and is one of the better Virgo galaxies for small telescopes. A small 80mm (3.1-inch) refractor reveals an elongated glow of light with a bright centre surrounded by a large outer envelope of nebulosity. It takes high magnifications well, so don't be afraid to push up the power especially when the seeing conditions are good.
In total, this galaxy spans 6.9 x 3.7 arc minutes of apparent sky but of course through the eyepiece it appears much smaller. With a medium size 200mm (8-inch) reflector, M88 displays subtle changes in brightness especially along the edges. The core is well defined, condensed and bright.
M88 is located 53 million light-years distant, which corresponds to an actual diameter of 105,000 light-years. It's estimated to contain about 400 billion stars and, to date, one supernova (SN 1999cl) has been observed. It peaked at magnitude +13.6 and was within the range of larger amateur scopes.
M88 Data Table
|Object Type||Spiral galaxy|
|Distance (light-years)||53 Million|
|RA (J2000)||12h 31m 59s|
|DEC (J2000)||+14d 25m 15s|
|Apparent Size (arc mins)||6.9 x 3.7|
|Number of Stars||400 Billion|
|Notable Feature||Member of the Virgo Cluster of galaxies|