Ursa Major – the great bear

August 7, 2016

Astronomy

biggerbearThe Greater Bear, Ursa Major, is probably the most significant constellation in the northern sky because it contains the Big Dipper.

The Big Dipper is a thing with a thousand names. It’s the most obvious and easiest to recognize of all the star groups. To the British it is the plow. To the Chinese it is the wagon. The Vikings called it the wagon also. If you imagine adding wheels it does sort of resemble a wagon but then so does your grandmother.

Another fun fact is that people can use the two stars in the front of the bowl to find the north star. This was especially popular for African Americans who were tired of picking cotton without pay and wanted to head north where there was more freedom and less cotton. A banjo picker named Peg-Leg Joe even wrote a song about it.
Finding_North
The Native American Indian tribes in the northeast U.S., like the Musquakie, Iroquois, and other linguistically related tribes, call these stars the Hunters and the Bear. I realize it might be tempting to conjure up some sort of ancient cultural connection between the purely American bear of this story and the old-world Ursa Major bear. Please don’t.
taxibear
Anyway the three stars in the handle are the hunters and the bowl of the dipper is the bear. The middle hunter is a star we call Mizar. If you look close there is a tiny star next to Mizar which we call Alcor. In the story, Alcor is a little dog named “Hold Tight” who is along for the thrill of the chase. On autumn evenings the chase moves low along the northern horizon where blood dripping from the bear’s arrow wounds stains the trees red and brown each year, which clears up that botanical mystery.
cloudwinnieDeeper Dipper
The whole of Ursa Major is a major chunk of the northern sky, much bigger than just the dipper itself. There is a lot of tasty deep sky to be served up here, but I’ll stick to the main course.
uma
m81m82M81 and M82 are a pair of galaxies that are close enough together to be found with a single effort.

The graceful M81 is a well-behaved spiral. I’m sure its inhabitants are quite proud. But M82 is an irregular rebel which shows the apparent discomfort of having eaten something disagreeably spicy. It’s nickname is the “Cigar Galaxy” but in a small scope it’s shaped more like a badly rolled joint.

Back in January 2014 astronomers observed a supernova in M82, which appeared for a few weeks as a tiny extra dot in the hazy smudge of the disk. I saw it from my yard in a 12″ scope so I have that going for me.

m97There is an excellent planetary nebula underneath the bowl of the dipper, called M97. It’s also called the Owl Nebula because it has a round face, and big eyes, and it needed a name.

What you are seeing with M97 is the death-shroud of an older star that is recycling some of its outer layers into the interstellar medium. If you are looking to buy some carbon, nitrogen, and oxygen, this would be a place to get that stuff wholesale. This is what happens when stars retire from the main sequence and move to a quiet cul-de-sac in the suburbs of the H-R diagram.

mommabearyUrsa Major also includes M40. Of all the objects that Charles Messier recorded in his famous catalog, M40 is the certainly the least important and the least interesting. Ironically I guess that makes it interesting. It’s not a galaxy or a nebula or anything awesome like that. It’s just two stars. Maybe Charles wrote down the coordinates wrong, or maybe his scope was out of focus, or there was horse hair on the lens. Whatever, it’s hideous, it’s stupid. Don’t look at it.

Carpe Noctem.

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