Constellation of the Month: Orion

December 31, 2018 | By Peter Forrester

We’ve had several clear or partially clear nights recently. If you’ve looked up just slightly while facing east about 6 or 7 pm, chances are you’ve seen the Constellation of the Month.

Orion is one of the brightest and best-known constellations in the sky. Even people who know very little about astronomy or stars may recognize this particular shape in the sky. It is located very close to several of the “zodiac” constellations. Due to its brightness, and familiarity, it can be used to find many other constellations. Thus it seems an appropriate choice for the first constellation of the month.

Orion is sometimes called a winter constellation. In most of the summer it is not visible in the Northern Hemisphere, and at other times it can only be seen in the early morning. I recommend dressing up and braving all this cold weather to get a good look at this thing; it really is the best time of year to see it. It’s so bright, I can catch glimpses of it while driving home in the evening (not that you should be looking at stars behind the wheel, of course).

Orion has been pictured as a hunter since the time of the early Greeks. The seven brightest stars form a shape like an hourglass. Four make up his shoulders and feet, and the other three are his belt. He is holding something in front of him, interpreted as a shield. There are also many dimmer stars, and several nebulae (clouds of dust and gas out in space) which can be seen with the naked eye. Looking at these objects through binoculars is an even more wonderful experience.

To the left of Orion are found the two dogs, Canis Minor and Canis Major, and above him to the right, on the other side of the shield, is Taurus the Bull. Above him and a bit to the left is the constellation Gemini, the twins. Taurus and Gemini you might recognize as the names of two zodiac constellations.

Rigel is usually the brightest star in Orion, and the seventh brightest star in the night sky. I say “usually” because the star Betelgeuse (pronounced BEETLE-juice) is a variable star, and is sometimes brighter than Rigel. Rigel is considered to be the left foot of Orion, though it appears on the right side from our perspective. The second and third brightest stars in Orion, the two shoulders, are called Betelgeuse and Bellatrix. They have both had their names borrowed for popular works of fiction. For some reason Rigel’s name has not been as popular. The other bright stars (among the 7 brightest) include Saiph, the other foot, and the three in the belt are called Alnitak, Alnilam, and Mintaka. Sidenote: many star names come from Arabic, perhaps because of an early Muslim astronomer (Abd al-Rahman al-Sufi) who made detailed drawings and descriptions in his book, called Book of Fixed Stars, published around 964 A.D.

I am sure many readers are interested in knowing how you can use Orion to locate other constellations. There are many good illustrations of this online. A simple search will bring up many of these. My favorite drawings that I’ve found so far are found on a site of educational articles called Owlcation; see the first reference below. The article has some typos but the drawings are great. The author also recommends two free astronomy software programs, which I plan to review in the near future.

Following the line of Orion’s belt down and to the East (left), you come to Sirius, the brightest star in the night sky, which is part of the large dog, Canis Major. Following the belt the other way leads you to Aldebaran, the brightest star in Taurus. You can also draw a line from the bottom right star, Rigel, up through the top left, Betelgeuse, and this leads you to Castor and Pollux, the two brightest stars in Gemini. And a line through the shoulders, down and to the East leads you to Procyon, the brightest star in the small dog, Canis Minor.

Besides Taurus, Gemini, and the two dogs, you can also locate the Pleiades star cluster, as well as a constellation called Cetus, the Whale by drawing lines using stars in Orion. There are also two patterns of stars or asterisms around and including Orion that can be used to locate various constellations. The Winter Triangle contains Sirius, Procyon and Orion’s Betelgeuse. The larger Winter Circle or Hexagon is composed of six stars, one of which is Rigel.

Orion has had many different names in different ancient nations’ descriptions and mythology. It has been identified with the Egyptian god Sah, and with the founder of the Armenian nation, Hayk. It has not always been seen as a hunter, or even as a man. There is much more of the mythology and history to be found in the Wikipedia article, including a Greek story about why Orion and the constellation Scorpio are never in the sky at the same time.

People in both the Northern and Southern Hemispheres can see Orion in the early evening right now, though it is summer for the people in the Southern Hemisphere. It also appears upside down there, from my northern perspective in Milton, and above rather than below the ecliptic. It is almost overhead for people near the Equator, however, and not visible at all at the South Pole, because the Sun doesn’t set during summer there.


See also: Observing the Planets: Venus | What Is the Zodiac, Anyway? | Skies Over Milton, December Edition


References:

Owlcation. (Updated 2018, March 13). Using Orion to find Stars and Constellations. By RaulP. Retrieved from https://owlcation.com/stem/Using-Orion-to-find-Stars-and-Constellations-part-1

Wikipedia. (2018, December 31). Book of Fixed Stars. Retrieved from https://en.wikipedia.org/wiki/Book_of_Fixed_Stars.

Wikipedia. (2018, December 31). List of Arabic Star Names. Retrieved from https://en.wikipedia.org/wiki/List_of_Arabic_star_names.

Wikipedia. (2018, December 31). Orion (constellation). Retrieved from https://en.wikipedia.org/wiki/Orion_(constellation).

Wikipedia. (2018, December 31). Winter Hexagon. Retrieved from https://en.wikipedia.org/wiki/Winter_Hexagon.

Author: Peter Forrester

I have been interested in astronomy and stargazing for many years, and now delight to offer some of my learning to others through my weekly blog posts.

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