M82 is a superb irregular galaxy located in the constellation of Ursa Major. It has an apparent magnitude of +8.4 and is visible with binoculars. Separated by only 38 arc minutes from M82 is an even brighter and equally stunning galaxy, M81. However, they are very different objects. M81 (mag. +6.9) appears almost face-on, is of a grand spiral deign and therefore exhibits prominent near perfect and well defined spiral arms. On the other hand, M82 (mag. +8.4) is edge on, appears long and thin and is known as the Cigar galaxy. It's classified as the prototype starburst galaxy in which stars are forming at exceptionally high rates.

These two objects are the largest members of the Ursa Major or M81 group of galaxies, which at a distance of 11.7 million light-years is one of the closest groups of galaxies beyond the Local Group. Spatially, M81 and M82 are close and are physically separated by only about 150,000 light-years. When seen through binoculars and telescopes at low powers they form a striking pair.

Both M81 and M82 were discovered by Johann Elert Bode on December 31, 1774. Pierre Mechain then independently rediscovered them in August 1779. He reported his observations to Charles Messier, who added both galaxies to his catalogue on February 9, 1781. Finding M82 is not particularly difficult as the Plough asterism of Ursa Major can be used as a starting point. First focus on Dubhe (α UMa - mag. +1.8) the northwest corner star of the bowl. The M81 / M82 pair is located 10 degrees northwest of this star, with M82 positioned directly north of M81.

The galaxies are best seen from the Northern Hemisphere during the months of March, April and May. From locations north of +21 degrees they are circumpolar and always visible.

M82 Starburst Galaxy by the Hubble Space Telescope (NASA, ESA, and The Hubble Heritage Team (credit:- STScI/AURA))

Finder Chart for M82 (credit:- freestarcharts)

Finder Chart for M82 - pdf format (credit:- freestarcharts)

M82 appears as a faint thin rod of light in binoculars, while M81 looks large and diffuse. The difference in size and shape of these two galaxies is apparent. Small 80mm (3.1-inch) telescopes at low powers show M82 as a slim grey needle of uniform light. A 150mm (6-inch) or 200mm (8-inch) instrument at high magnifications reveals dusty patches that cross the sharp surface of M82. The centre region is brighter that the edges.

In total, M82 spans 11.2 x 4.3 arc minutes of apparent sky. At a distance of 11.5 million light-years this corresponds to an actual diameter of 38,000 light-years, although it's less than half the diameter of M81 (90,000 light-years). Together, the pair form a popular visual and imaging target for amateur astronomers.

M82 is believed to contain at least 30 billion stars. On January 21, 2014, a bright type 1a supernova (SN 2014J) was discovered by Stephen J. Fossey and his students at the University College London (UCL) observatory in London.

M82 Data Table

Messier82
NGC3034
NameCigar Galaxy
Object TypeStarburst galaxy
ClassificationIrregular
ConstellationUrsa Major
Distance (light-years)11.5 Million
Apparent Mag.+8.4
RA (J2000)09h 55m 51s
DEC (J2000)+69d 40m 43s
Apparent Size (arc mins)11.2 x 4.3
Radius (light-years)19,000
Number of Stars>30 Billion
Notable FeaturesPrototype starburst galaxy. Member of the M81 Group of galaxies

Sky Highlights - July 2017

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for July

Meteor Shower
Southern Delta Aquariids (Aquarids) meteor shower peaks on July 29

Northern Hemisphere
Evening
West:- Mercury (mag. -0.5 to +0.3) (second half of month)
Southwest:- Jupiter (mag. -2.0)
South:- Saturn (mag. +0.2)
Midnight
West:- Jupiter
South:- Saturn
East:- Neptune (mag. +7.8)
Morning
Southwest:- Saturn
South:- Neptune
Southeast:- Uranus (mag. +5.8)
East:- Venus (mag. -4.1)

Southern Hemisphere
Evening
West:- Mercury (second half of month)
Northwest:- Jupiter
East:- Saturn
Midnight
West:- Jupiter
North:- Saturn
East:- Neptune
Morning
West:- Saturn
North:- Neptune
Northeast:- Venus, Uranus

Deep Sky

Small telescopes:-
Messier 13 - M13 - Great Hercules Globular Cluster
Messier 92 - M92 - Globular Cluster
Messier 11 - M11 - The Wild Duck Cluster (Open Cluster)
Messier 7 - M7 - The Ptolemy Cluster (Open Cluster)
Messier 6 - M6 - The Butterfly Cluster (Open Cluster)
Messier 4 - M4 - Globular Cluster
Messier 8 - M8 - Lagoon Nebula (Emission Nebula)
Messier 16 - M16 - Eagle Nebula (Emission Nebula with Open Cluster)
Messier 20 - M20 - Trifid Nebula (Emission and Reflection Nebula)

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