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APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Bright Spiral Galaxy M81
Explanation: One of the brightest galaxies in planet Earth's sky is similar in size to our Milky Way Galaxy: big, beautiful M81 . The grand spiral galaxy can be found toward the northern constellation of the Great Bear ( Ursa Major ). This superbly detailed image reveals M81's bright yellow nucleus, blue spiral arms, tell tale pinkish star forming regions, and sweeping cosmic dust lanes with a scale comparable to the Milky Way. Hinting at a disorderly past, a remarkable dust lane actually runs straight through the disk, to the left of the galactic center, contrary to M81's other prominent spiral features . The errant dust lane may be the lingering result of a close encounter between between M81 and its smaller companion galaxy, M82 . Scrutiny of variable stars in M81 has yielded one of the best determined distances for an external galaxy -- 11.8 million light-years. M81's dwarf companion galaxy Holmberg IX can be seen just above the large spiral.
| Date | October 17, 2015 |
|---|---|
| Credit | Image Credit & Copyright: Ken Crawford ( Rancho Del Sol Observatory ) |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |