Composite photo by NASA, ESA, and The Hubble Heritage Team
The large “grand design” spiral galaxy M81 is located 11.6 million light-years away – not that distant in cosmic terms. The spiral arms, which wind all the way down into the nucleus, are made up of young, bluish, hot stars formed in the past few million years. The greenish regions are dense areas of bright star formation. The ultraviolet light from hot young stars are fluorescing the surrounding clouds of hydrogen gas. The galaxy’s central bulge contains much older, redder stars. And at the core of the galaxy lies a black hole 15 times the mass of our own Milky Way’s black hole and 70 million times the mass of our own sun.
Since M81 is tilted in relation to our line of sight, we get a “birds-eye view” of the spiral structure which is similar to our Milky Way, giving us a good view of the typical architecture of spiral galaxies like our own. Though the galaxy is 11.6 million light-years away, the vision of the NASA/ESA Hubble Space Telescope is so sharp that it can resolve individual stars, along with open star clusters, globular star clusters, and even glowing regions of fluorescent gas.
M81 is one of the brightest galaxies that can be seen from Earth. It is high in the northern sky in the constellation of the Great Bear, and can just be seen by the naked eye.
Close-up of stars within the M81 galaxy
The Hubble Space Telescope’s view is so sharp that it can resolve individual stars, along with open star clusters, globular star clusters, and even glowing regions of fluorescent gas.