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Birthday · September 17, 2017

Bright Spiral Galaxy M81

September 17, 2017

You share your birthday with the light of distant galaxies that has been traveling for millions of years just to arrive here, now, alongside...

Bright Spiral Galaxy M81

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APOD published September 17, 2017. Credit: Roberto Colombari & Robert Gendler. A publication-date match, not a photo taken on your date. Independent of NASA.

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Bright Spiral Galaxy M81

Original APOD · September 17, 2017

One of the brightest galaxies in planet Earth's sky is similar in size to our Milky Way Galaxy: big, beautiful M81. This grand spiral galaxy can be found toward the northern constellation of the Great Bear (Ursa Major). This superbly detailed view reveals M81's bright yellow nucleus, blue spiral arms, 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 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. Free Download: The 2018 APOD Calendar

Image credit: Roberto Colombari & Robert Gendler

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