Messier 81 (lower right) & 82 (M82) Celestron Origin image 60 min 360 exposure (c) DE Wolf 2024

Messier 81 (M81) and Messier 82 (M82) are located in the northern sky in the Big Bear or Ursa Major. They are named the “Bode’s Galaxy” and the “Cigar Galaxy,” respectively, They were cataloged by French astronomer Charles Messier in 1774 as part of his mission to identify and catalog celestial objects that could be mistaken for comets. Messier 81 is a spiral galaxy, while Messier 82 is a peculiar galaxy, often classified as a starburst galaxy due to its unusual structure and intense star formation.

These two galaxies are part of what are referred to as the M81 group, a collection of gravitationally connected and interacting galaxies. This pair dominates the group visually but it also contains several smaller galaxies, such as NGC 3077, NGC 2976, and NGC 2366.

Galaxies generally come in groups. The members of our Milky Way’s group, referred to as the “Local Group,” are extensive and include: the Milky Way itself, the Andromeda galaxy (M31), the Triangulum Galaxy (M33). Additionally, there are so-called dwarf galaxies: Large Magellanic Cloud, (LMC), Small Magellanic Cloud (SMC), Sagittarius Dwarf Elliptical Galaxy, Ursa Minor Dwarf Galaxy, Draco Dwarf Galaxy, Carina Dwarf Galaxy, Leo I and Leo II. Our Local Group also contains a variety of other smaller dwarf galaxies that are gravitationally bound to the larger galaxies. These include: Fornax Dwarf Galaxy, Phoenix Dwarf GalaxyAndromeda II, Andromeda III, and the WLM Galaxy (Wolf-Lundmark-Melotte). The extensive list illustrates the extent of gravitational clustering in the universe and by connection the incredible distances over which gravity extends and shapes the structure of the universe.

Messier 81, or Bode’s Galaxy, is one of the brightest galaxies in the Messier catalog and stands out due to its well-defined spiral structure. It is located approximately 12 million light-years from Earth and is part of the M81 group, which consists of a collection of galaxies in close proximity to one another. With a diameter of around 90,000 light-years, M81 is a relatively large galaxy, comparable in size to our Milky Way.

One of the most striking features of M81 is its spiral arms, which are richly populated with stars, gas, and dust. These arms are the sites of ongoing star formation, and the galaxy is thought to be relatively stable, with a low rate of active starburst activity. The central region of M81 contains a bright, active supermassive black hole that likely plays a role in regulating the galaxy’s dynamics. Its steady state contrasts sharply with the more energetic activity seen in its neighboring galaxy, M82.

Messier 82, known as the Cigar Galaxy due to its elongated, cigar-like shape. M82 is a peculiar galaxy, often classified as a starburst galaxy. This means it is experiencing an exceptionally high rate of star formation, far higher than typical galaxies like our Milky Way. The intense starburst activity in M82 is thought to be a result of interactions with nearby galaxies, particularly Messier 81.

Unlike the relatively calm Messier 81, M82 is a turbulent galaxy, with massive amounts of gas and dust fueling the rapid birth of new stars. The central region of M82 hosts a vigorous outflow of gas and energy, creating a dramatic galactic wind. This outflow is thought to be the result of the starburst activity and may eventually expel a significant portion of the galaxy’s gas, limiting future star formation.

The two galaxies continue to interact and there is some evidence that this gravitational interaction with M81 is responsible for the starburst activity of M82. They are believe to exchange material and may at some point merge with one another.

Never setting in northern skies, they are a favorite of amateur astronomers. The image of Figure 1 is a 360 frame 1 hour exposure taken with my Celestron Origin. I framed it so as to bring both galaxies into the image to suggest their gravitational pairing and interaction.