We shouldn’t neglect to show appreciation to old friends, and yet it has been many years since I have dedicated a column to perhaps the most recognizable constellation in the winter sky – Orion. Many people unfamiliar with the night sky can at least recognize the three stars of Orion’s Belt. Above and below the belt, Betelgeuse and Rigel are two of the brightest stars in the night sky.
Orion is the great hunter in Western mythology. He is accompanied in the sky by two dogs, seen as Canis Major and Canis Minor. Toward the west, he is facing Taurus, the bull. One Greek mythology story has Orion offending one of the gods, who then sends a scorpion to kill him. He is stung and dies but is first able to kill Scorpius. These two mortal enemies were then placed on opposite sides of the sky so they are never above the horizon at the same time.
Betelgeuse and Rigel are two convenient stars for pointing out differences in star color. Betelgeuse is similar in apparent brightness to Rigel but is noticeably redder in color. Betelgeuse is one of the few stars to ever have its diameter measured directly. If Betelgeuse took the place of our sun, the star’s surface would be somewhere near the orbit of Jupiter.
Betelgeuse is also a variable star. In early 2020, it dimmed by a factor of three. Because it is a red supergiant nearing the end of its life, there were many online discussions that it would become a supernova during the pandemic. Although it will become a supernova within a short time, on an astronomical scale that means sometime within the next 100,000 years.
The belt stars are (from east to west) Alnitak, Alnilam and Mintaka. They appear close to each other in the sky, but they are at greatly differing distances. Alnitak is approximately 700 light years distant, Mintaka is around 900 and Alnilam is about 1350 light years away.
The belt lies almost right on the celestial equator, so Orion is one of the few constellations visible to both Northern and Southern hemisphere observers. Because it is on the equator, Orion is due east when it rises and due west when it sets. The belt also makes a good pointing tool. Following the line of stars to the west leads to Aldebaran in Taurus. Eastward, they point to Sirius, in Canis Major.
As with many of the brighter stars in the night sky, the belt stars are blue or blue-white supergiants. Burning their fuel at rates hundreds of thousands of times that of the sun, these stars will be very short-lived.
Adjacent to Alnitak are two prominent nebulae. The Flame Nebula and the Horsehead Nebula are extremely challenging objects to observe visually, partially because of their proximity to such a bright star. However, both nebulae do show up in easily in photographs.
Below Orion’s Belt, representing either his sword or his manly parts, is M42, the Orion Nebula. It is the brightest star-forming region in the sky and is one of the best objects to view through either binoculars or a telescope at almost any magnification.
You still have a chance to see the long-period Comet C/2022 E3 (ZTF) as it speeds toward the outer solar system. Rather than the interesting green that shows well in photographs, you will most likely see a faint gray smudge like I saw through binoculars.
The two brightest planets, Venus, at magnitude -4.0, and Jupiter, at magnitude -2.1, are in the western sky after sunset. They are appearing closer and closer throughout February, and their conjunction will be on March 1. On Feb. 21 and 22, the crescent moon will also be in the same part of the sky.
Comet C/2022 E3 (ZTF)
Astronomy picture of the day
An Astronomer’s forecast for Durango
Old Fort Lewis Observatory
Charles Hakes teaches in the physics and engineering department at Fort Lewis College and is the director of the Fort Lewis Observatory.