Posted by on Feb 9, 2013 in Constellation Of the Month | 0 comments

Ursa Major is one of the oldest of the constellations, and is included in the forty-eight listed by Ptolemy. In western mythology Ursa Major was originally named Callisto.  In Hindu astronomy it is named as Sapta Rishi, meaning the ‘Seven Great Sages. The seven stars are very important in Taoist astrology. Sometimes there are said to be nine stars besides the seven visible stars, two invisible “attendant” stars, one on either side of the star Alkaid. Legend has it that there used to be 9 stars (北斗九星) but 2 had since faded and that those who can see the 2 unseen stars will lead a long life. The Goddess Doumu is said to have given birth to the nine stars, which make up the constellation.

Star Visual Magnitude Spectrum Absolute Magnitude Distance (Lt Years)
Alioth 1.79 Ao 0.2 68
Dubhe 1.81 Ko -0.7 107
Alkaid 1.87 B3 -2.1 210
Mizar 2.06 A2 0.1 88
Merak 2.37 A1 0.5 78
Phad 2.44 Ao 0.2 90
Mergez 3.32 A3V var 1.33 81

 

Buruj Biduk (The ladle) is the formation’s name in Malaysia. In Mongolia, it is known as the Seven Gods (Долоон бурхан). In parts of rural India, it is known as the Samantha formation. An Arabian story has the four stars of the Plough’s bowl as a coffin, with the three stars in the handle as mourners, following it.

The above listed seven stars make up the famous Plough, which our colonial cousins refer to as the Big Dipper. The constellation is so conspicuous that it cannot be overlooked. During this time of year it is almost overhead in the northern horizon. The deep sky objects found within Ursa Major are listed below.

M-81 This is a large and beautiful spiral galaxy, 10′ long and 4′ wide, oriented NNW-SSE. It has a bright core with a stellar nucleus, and spiral arms can be seen, especially with averted vision.

M-82 A beautiful object! This peculiar galaxy is 10’x2-3′, oriented NE-SW. It has slightly tapering ends, and a great amount of mottling across its length can be seen. The southern edge appears flatter, and it seems to be “pinched” near the centre on this side. Fascinating.

M-97 The Owl Nebula. This large planetary nebula is almost 3′ in diameter, and appears as a grey puff of light, slightly brighter in the centre. At times, especially with averted vision, the “eyes” of the owl can be seen as two slightly darker spots.

M-101 The Pinwheel Galaxy. A large face-on spiral galaxy with low surface brightness. It is about 7′ in diameter, with a brighter core surrounded by an envelope, which sometimes can be seen to be spiral arms.

M-108 Large, about 10’x3′ extended ENE-WSW. This galaxy has an evident central bulge, a stellar nucleus, and tapering ends. The western end appears to be tapered more than the eastern end, and dark markings are seen along its northern edge.

M-109 8’x4′, oriented ENE-WSW, with a faint stellar nucleus. Spiral arms can be seen leading to the north and south.

NGC 2841 A very pretty galaxy. 7’x2-3′, oriented NNE-SSW, with a sharply brighter core and stellar nucleus. Dark markings can be seen, especially east of the nucleus.

NGC 3079. Fascinating. 6’x2′ with an obvious central bulge and extended N-S. Broadly concentrated to the centre with pointed ends. At times, the ends appear curled: the north end to the west, and the south end to the east. Very pretty.

NGC 3631 Large and impressive, this galaxy is roughly circular and 5′ in diameter. The core is about 1′ in diameter and has a stellar nucleus. Averted vision shows arms spiralling from the north to the east.