M110 is a dwarf elliptical galaxy located in the constellation of Andromeda. It's one of many satellite galaxies orbiting M31, the famous and spectacular Andromeda galaxy. Of these, at least 14 are dwarf galaxies with M110 being the second brightest of them (after M32). The galaxy is classified as Hubble type E5 and designated as "peculiar" due to unusual dark structures that are probably due to dust clouds.

At magnitude +8.7, M110 is a very challenging binocular object. Although quite large - it covers 22 x 11 arc minutes of apparent sky - it suffers from a low surface brightness and hence even a small amount of light pollution can render it a difficult object to spot with small telescopes.

Surprisingly, Charles Messier never included M110 in his famous list. However he depicted it, together with M32 on a drawing of the Andromeda galaxy he made on the August 10, 1773. Caroline Herschel independently discovered the galaxy on August 27, 1783 and much later in 1967, Kenneth Glyn Jones suggested assigning the galaxy a Messier number. Although now commonly known as M110, it's still often referred to in many texts and charts by its New General Catalogue number, NGC 205.

To find M110, first locate the Andromeda Galaxy, which is positioned northeast of the famous "Great Square of Pegasus". Of the four stars of the square, only three of them actually belong to Pegasus. The northeast corner star and brightest of the four at magnitude 2.1, Alpheratz (α And) is part of neighbouring Andromeda. Located 7 degrees to the northeast of Alpheratz is δ And (mag. 3.3) and a further 8 degrees to the northeast of δ And is mag. 2.1, Mirach (β And). The Andromeda galaxy is a further 8 degrees to the northwest of Mirach at the end of a line connecting Mirach with μ And and ν And. M110 is located 36 arc minutes northwest of the centre of M31.

The galaxies are best seen from the Northern Hemisphere during the months of September, October and November.

M110 Dwarf elliptical galaxy (Johannes Schedler - Panther Observatory - www.panther-observatory.com)

Finder Chart for M110 (also shown M31, M32 and M33)

Finder Chart for M110 (also shown M31, M32 and M33) - pdf format

In a 80mm (3.1 inch) telescope M110 appears very dim and diffuse. It has a soft, low luminosity without a bright point core (unlike M31 and M32). In a 200mm (8-inch) scope, M110 appears as a large oval nebulosity that's slightly brighter towards the centre. The edges are diffuse.

M110 is located 2.69 million light-years from Earth, which is about 150 million light-years further from us than M31. Its actual diameter is 17,000 light-years and the galaxy is estimated to contain 10 billion stars. Surrounding M110 are at least 8 globular clusters, the brightest of them (G73) is of 15th magnitude which is visible in very large amateur telescopes. In 1999, R. Johnson and M. Modjaz of the University of California at Berkeley on behalf of the Lick Observatory Supernova search discovered a nova in M110 at magnitude +18.

M110 Deep Sky Data Table

Messier110
NGC205
Object TypeDwarf elliptical galaxy
ClassificationE5
ConstellationAndromeda
Distance (kly)2,690
Apparent Mag.8.7
RA (J2000)00h 40m 22s
DEC (J2000)41d 41m 26s
Apparent Size (arc mins)21.9 x 11.0
Radius (light-years)8,500
Number of Stars10 Billion
Notable FeatureSatellite galaxy of M31

Sky Highlights - March 2017

Comet
Comet 41P/Tuttle-Giacobini-Kresak now visible with binoculars as it heads towards perihelion

Mercury
Mercury heading towards greatest elongation east

Minor Planet
Vesta now visible with binoculars and small telescopes.

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for March 2017

Northern Hemisphere
Evening
West:- Venus (mag. -4.8 to -4.1 - first half of month), Mars (mag. +1.3 to +1.5), Uranus (mag. +5.9), Mercury (mag. -1.5 to -0.4 - second half of month)
Midnight
Southeast:- Jupiter (mag. -2.3 to -2.5)
Morning
Southwest:- Jupiter
Southeast:- Saturn (mag. +0.5)

Southern Hemisphere
Evening
West:- Venus (first half of month), Mars, Uranus
Midnight
North:- Jupiter
East:- Saturn
Morning
West:- Jupiter
Northeast:- Saturn
East:- Neptune (mag. +8.0 - second half of month)

Deep Sky
Naked eye / binoculars:-
Melotte 111 - Mel 111 - The Coma Star Cluster (Open Cluster)
Messier 44 - M44 - The Praesepe (Open Cluster)

Telescopes:-
Messier 67 - M67 - Open Cluster
Messier 51 - M51 - The Whirlpool Galaxy (Spiral Galaxy)
Messier 97 - M97 - The Owl Nebula (Planetary Nebula)
Messier 101 - M101 - The Pinwheel Galaxy (Spiral Galaxy)
Messier 65 – M65 – Spiral Galaxy
Messier 66 - M66 - Intermediate Spiral Galaxy
Messier 95 - M95 - Barred Spiral Galaxy
Messier 96 - M96 - Intermediate Spiral Galaxy
NGC 4244 - Spiral Galaxy
NGC 4565 - Needle Galaxy - Spiral Galaxy

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