Ursa Major (the Big Bear)

Ursa Major Constellation Facts

- Ursa Major is visible all year in the Northern hemisphere (and that means in Somerville!).
- The constellation is partially visible in some northerly regions of the Southern hemisphere.
- Ursa Major is Latin for Great Bear, although the constellation is based on Greek mythology.
- Ursa Major is associated with the nearby constellation of Ursa Minor (Little Bear).
- The very recognizable Big Dipper, also known as The Plough, is part of the Ursa Major constellation.
- The Big Dipper is an asterism, which are stars which form simple patterns but are not constellations.
- The two stars which form the outer bowl of the Big Dipper point towards the North Star, Polaris.
- Polaris is the brightest star in the constellation of Ursa Minor.
- The tail of Great Bear includes the brightest star in the Ursa Major constellation, Alioth.
- Native North Americans also perceived the pattern of stars as a bear.

Description

Ursa Major, the Greater Bear is the third largest constellation in the sky. What is more familiar however, are the seven stars which make up the rump and tail of this animal. We know them as the Big Dipper.

Many people mistakenly think that the Big Dipper is a constellation but it isn't, it is something called an asterism. An asterism is a small easily recognizable formation of stars that is usually part of a larger constellation. In this case, the Big Dipper is part of the constellation Ursa Major.

Another thing this constellation is known for is the "pointer stars." These are the two outside stars in the bowl of the dipper. A line drawn through them points to the north star.

In the Boston area, we are able to see Ursa Major all year long (as long as it is a clear night, of course).

Mythology

One Greek myth tells the story of the nymph Callisto, who was turned into a bear by the gods. On accident, her son, a human, was about to kill the bear (her mother). Zeus, the head god, stopped this by turning them both into bears and flinging them up into the sky. The way Zeus got the bears into the sky explains why their tails are so long, apparently Zeus grabbed them by their tails and swung them around over his head and finally flung them into the sky, and that is why these two bears have long tails!

This is just one story about this constellation, and its related constellation Ursa Minor (the Little Dipper). Cultures from all over the world have their own stories about them!

The formation of Ursa Major took 200,000 years. This short video shows in a very sped up model how Ursa Major formed:

Main Stars in the Ursa Major Constellation

AlkaidAlso known as Eta Ursae Majoris, Alkaid is a bluish-white main sequence star with surface temperatures around 3 times that of the sun, it's also around 3 and half times larger in radius than the sun.

Mizar-AlcorA six star system around 80 light years from Earth, Mizar consists of two pairs of binary stars while Alcor consist of one pair, the two are separated by a distance of one light year.

AliothAlso known as Eta Ursae Majoris, at a distance of around 80 light years from Earth Alioth is the brightest star in the constellation, it has surface temperatures twice that of the sun with a radius around 4 times larger.

MegrezA white main sequence star one and a half times larger in mass and radius than the sun, also known as Delta Ursae Majoris the star is around 60 light years from Earth.

DubheAlso known as Alpha Ursae Majoris, Dubhe is an orange giant star around 120 light years from Earth, Dubhe is the second brightest star in the constellation.

Muscida

At a distance of around 180 light years from Earth Muscida is a yellow giant star with a radius 14 times larger than the sun, the star is also known as Omicron Ursae Majoris.

Talitha

Also known as Iota Ursae Majoris, Talitha is a four star system consisting of two pairs of binary stars around 45 light years from Earth.

Merak

A white main sequence star with around three times the mass and radius of the sun, also known as Beta Ursae Majoris the star has surface temperatures around twice as hot as the sun, drawing an imaginary line through Merak and Dubhe will point you to the North star.

Phecda

Another white main sequence star similar in radius and mass to Merak, also known as Gamma Ursae Majoris the star is around 80 light years from Earth.

Tania Borealis

At around 140 light years from Earth this white star has around 2 and half times the mass and radius of the sun.

Tania Australis

A red giant star around 240 light years from Earth, Tania Australis is around 75 times larger in radius than the sun.

Alula Borealis

An orange giant star around 400 light years from Earth, Alula Borealis is around 60 times larger in radius than the sun.

Alula Australis

A four star system consisting of two pairs of binary stars around 30 light years from Earth, the primary stars in both pairs are sun like stars, while their companions are thought to be red dwarfs.

To Learn More:

BrainPop - Constellations - ask your teacher for the code

Sources:

http://starryskies.com/The_sky/constellations/ursa_major.html

http://www.solarsystemquick.com/universe/ursa-major-constellation.htm

Videos:

The number next to each star is its apparent magnitude, its brightness from our point of view on Earth, the lower the number the brighter the star in the night sky.

The Fable of the Big Dipper:

Another Fable About How the Big Bear and Little Bear Ended Up In the Sky Together:

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