M81, familiarly known as Bode’s Galaxy, is a spiral galaxy about 12 million light years away – a next door neighbor in the scale of the universe.  The Milky Way is believed to have a very similar spiral arm structure to M81, so that’s what we would look like if you could perch yourself out in space.  It lies in the constellation Ursa Major.  Its New General Catalog identifier is NGC 3031.

Johann Elert Bode was a renowned German astronomer who lived from 1747 – 1826.  He was the first to record seeing this galaxy, in 1774, although it was later independently noted by Charles Messier in his famous catalog (hence the appellation “M81”).  In 1801 Bode published the star map and catalog Uranographia, which included the most comprehensive listing of visible stars up to that time, along with 20 engraved star maps.  The volume introduced the concept of constellation boundaries, the invisible lines that partition the sky.  Constellation boundaries were taken up and refined by other celestial map makers.  There are other cosmic objects named after Bode: The Bode triplet, Comet Bode, Asteroid 998 Bodea, as well as the mathematical Bode’s Law, which characterized the relative distances between the Sun and planets. The relationships used to formulate the “law” were, in later centuries, found to be coincidental and unsupported by physics.

The large number of blue stars on the periphery of M81 are young and hot.  It’s somewhat unusual to find such star formation on the outer arms of a galaxy, and it’s thought that “recent” interactions with “nearby” galaxies, like NGC 3077 (not pictured here) have triggered the burst of star formation.  (Such terms are always relative to the unimaginably immense scale of the universe; “recent” meaning hundreds of millions of years, and “nearby” meaning hundreds of thousands of light years.)

The blue patch at upper right is the dwarf galaxy Holmberg IX, a satellite galaxy of M81.  Not having an identifiable discrete structure, it is classified as a Magellanic irregular galaxy; that is, similar to the Magellanic cloud satellite galaxies of our Milky Way.  Containing mostly stars less than 200 million years old, it has the youngest stellar population of any nearby galaxy. Its older red stars are thought to have come from interactions with M81 itself, or neighboring galaxy M82 (not pictured here).