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Circumpolar Constellations Help (page 2)

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By — McGraw-Hill Professional
Updated on Sep 15, 2011

Ursa Major

The so-called big dipper is formally known as Ursa Major , which means “big bear.” It is one of the most familiar constellations to observers in the northern hemisphere. In the evening, it is overhead in the spring, near the northern horizon in autumn, high in the northeastern sky in winter, and high in the northwestern sky in summer. It, like its daughter, Ursa Minor, is shaped something like a scoop (Fig. 2-2). The two stars at the front of the scoop are Dubhe and Merak , and are called the pointer stars because they are roughly aligned with Polaris. If you can find the big dipper, look upward from the scoop five or six times the distance between Dubhe and Merak, and you will find Polaris. To double-check, be sure that the star you have found is at the end of the handle of the little dipper.

Stars and Constellations Circumpolar Constellations Ursa Major

Figure 2-2. Ursa Major, also called the “big dipper,” is one of the best-known constellations in the heavens.

Cassiopeia

One of the north circumpolar constellations is known for its characteristic M or W shape (depending on the time of night and the time of year it is viewed). This is Cassiopeia , which means “queen.” Ancient people saw this constellation’s shape as resembling a throne (Fig. 2-3), and this is where the idea of royalty came in. In the evening, Cassiopeia is low in the north-northwestern sky in the spring, moderately low in the north-northeastern sky in the summer, near the zenith in the fall, and high in the northwestern sky in the winter.

Stars and Constellations Circumpolar Constellations Cassiopeia

Figure 2-3. Cassiopeia, also called the “queen,” looks like the letter M or the letter W. To the ancients, it had the shape of a throne.

Cepheus

As the queen sits on her throne, she faces her spouse, the king, the constellation whose formal name is Cepheus . This constellation is large in size but is comprised of relatively dim stars. For this reason, Cepheus is usually obscured by bright city lights or the sky glow of a full moon, especially when it is near the horizon. It has the general shape of a house with a steeply pitched roof (Fig. 2-4). In the evening, Cepheus is near the northern horizon in the spring, high in the north-northeast sky in the summer, nearly overhead in the fall, and high in the northwestern sky in the fall.

Stars and Constellations Circumpolar Constellations Cepheus

Figure 2-4. Cepheus, the “king,” resides in front of Cassiopeia’s throne. It has the shape of a house with a steep roof.

Draco

One of the largest circumpolar constellations, obscure to casual observers on account of its long, winding shape, is Draco , the dragon. With the exception of Eltanin , a star at the front of the dragon’s “head,” this constellation is made up of comparatively dim stars (Fig. 2-5). Draco’s “tail” wraps around the little dipper. The big dipper is in a position to scoop up the dragon tail first. In the evening, Draco is high in the northeastern sky in springtime, nearly overhead in the summer, high in the north-northwest sky in the fall, and near the northern horizon in the winter.

Stars and Constellations Circumpolar Constellations Draco

Figure 2-5. Draco, the “dragon,” has a long, sinuous shape with an obvious “head” and “tail.”

Perseus

Perseus is another circumpolar constellation with an elongated, rather complicated shape (Fig. 2-6). A mythological hero, Perseus holds the decapitated head of Medusa, a mythological female monster with hair made of snakes and a countenance so ugly that anyone who looked on it was turned into stone. Perseus is low in the northwestern sky in springtime, half above and half below the northern horizon in the summer, high in the northeastern sky in the fall, and nearly overhead in the winter.

Stars and Constellations Circumpolar Constellations Perseus

Figure 2-6. Perseus is a mythological hero who holds the severed head of Medusa. Its star Algol varies in brilliance because it is actually two stars that eclipse each other as they orbit around a common center of gravity.

Practice problems of this concept can be found at: Stars and Constellations Practice Problems

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