M81 is a classic 2-armed spiral galaxy in the constellation Ursa Major. Two long arms on opposite sides of the galaxy can each be traced for nearly one complete revolution about the center of the galaxy. Short arm segments also branch off from the main arms. This regular structure is given the name "Grand Design Spiral", in contrast to other galaxies where the arms are less well formed, shorter, and more difficult to connect together in a global pattern. M81 has been studied intensively by astronomers seeking to understand the underlying mechanisms by which spiral patterns form.

(Caption by Steve Kent)