Located in the constellation Ursa Major, M81 is an exemplary spiral galaxy. Its two main arms, tracing an S shape in the sky, are so perfectly formed that astronomers have called M81 a ΓÇ£grand-design spiral galaxy.ΓÇ¥ The arms can be resolved into star clusters and bright nebulae, and, if one looks closely, it is even possible to make out individual giant stars and bright H II regions.
M81ΓÇÖs central regionΓÇöone of the most dense nuclear regions knownΓÇöis dominated by old stars that emit a soft, amorphous glow.
The galaxy is not perfectly symmetrical: one of its arms appears slightly distorted, a disruption that probably results from gravitational interaction with the neighboring galaxy M82.
