Messier 81

Messier 81 (also known as NGC 3031 or Bode's Galaxy) is a spiral galaxy. It is in the constellation Ursa Major. It is large. It is about 12 million light-years from Earth. It has an active galactic nucleus (which has a supermassive black hole). For these reasons Messier 81 has been well studied by professional astronomers. The galaxy is large and very bright. This makes it a popular object for amateur astronomers to look at.

Messier 81 was discovered by Johann Elert Bode in 1774.  The galaxy is sometimes called "Bode's Galaxy".  In 1779,  Pierre Méchain and Charles Messier reidentified Bode's object.  They listed it as Messier 81 in the Messier Catalogue.

M81 is dusty.  Interstellar dust is found in the galaxy's spiral arms.  It is connected with star formation areas.  The hot blue stars in star formation areas heat the dust and the hot dust emits infrared energy from these areas.

Supernova
Only one supernova has been seen in Messier 81.  The supernova is named SN 1993J. It was discovered on 28 March 1993 by F. Garcia in Spain.  At the time, it was the second brightest supernova seen in the 20th century.

M81 Group

Messier 81 is the largest galaxy in the M81 Group.  The M81 Group is a group of 34 galaxies in the constellation Ursa Major.  This Group and the Local Group, containing the Milky Way, are close together in the Virgo Supercluster. 

Amateur astronomy
Messier 81 is about 10° northwest of Alpha Ursae Majoris.  Messier 81 and Messier 82 can both be easily seen using binoculars and small telescopes.

Related pages
 List of galaxies
 Messier catalogue
 New General Catalogue

References

Other websites

 StarDate: M81 Fact Sheet 
 M81, SEDS Messier pages
 SST: Messier 81 
 APOD: Bright Galaxy M81 (6/20/02)
 NightSkyInfo.com - M81, Bode's Galaxy 

 ESA/Hubble images of M81 
 Galaxy Messier 81 (Bode's Galaxy)
 Spitzer Image Gallery 
 Helkit Observatory 
 Deep image of the M81 Area

Category:Spiral galaxies