What’s Up in the Sky – January, 2021
Welcome Back Winter Constellations
Most people probably don’t consider January to be a time for going out and enjoying the wintry sky. After all, it’s usually cold and cloudy and often snowing. But on those rare occasions when the sky is clear, it is definitely worth the effort to step outside and enjoy the sights that the sky has to offer.
Part of the reason is because some of the year’s most beautiful and interesting constellations and stars are in view, conveniently located, and out at convenient times. Let’s start with Orion, the Hunter, one of the most easily recognizable patterns in the sky. As with most sky observing, timing is important, but not critical. If you go out tonight right after dark, it will be a challenge because Orion will just be rising low near the eastern horizon, and won’t be easily visible until about nine o’clock. As the month progresses though, it rises earlier until, by the end of the month, not only Orion, but also his friends will be dominating the southern sky.
Two patterns of stars stand out when viewing the Hunter – the four bright stars that form his torso and the three stars lined up to form his belt. Take this opportunity to scan the belt and sword with binoculars. See if you can tell which of the sword “stars” is not really a star at all, and which one appears to be a double star.
The two most famous and easily recognizable stars in Orion are Betelgeuse and Rigel, upper left and lower right of the four that make up his body. Betelgeuse is a red giant star that, if located where our Sun is, would extend out beyond Earth’s orbit. Rigel is a white giant 50 times bigger than the Sun. It will likely cool and expand and after tens of thousands of years until it too becomes a red giant.
Closer examination of the sword reveals that the middle “star” is actually the Great Orion Nebula, a complex and fascinating region of young, forming stars and glowing clouds of gas 20,000 times larger than our entire solar system. Embedded in the heart of the Great Nebula is the beautiful multiple star system known as the Trapezium, consisting of four hot young stars in a tight trapezoid-shaped cluster. Although the nebula itself is visible to the naked eye, you will need binoculars or a small telescope to see the Trapezium.
Just below the easternmost belt star lies a dark cloud of gas and dust silhouetted against a brighter region of glowing interstellar gas heated by the surrounding stars. Known as the Horsehead Nebula (it takes its name from its shape), its enormous size is almost beyond comprehension – you could fit a billion solar systems inside it. And the Horsehead is a tiny part of an even larger cloud that is only visible with the aid of large, specialized equipment. It is best seen by Googling online images.
So spend some time scanning Orion with binoculars and familiarizing yourself with this region of the sky. Next month I will guide you around Orion’s neighbors and visit nearby sights up in the sky.
This month in history:
Jan 1: Asteroid Ceres discovered by Giuseppe Piazzi – 1801
Jan 4: NASA cancels further production of Saturn V rockets – 1970
Jan 13: Galileo discovers Ganymede, moon of Jupiter – 1610
Jan 19: New Horizons spacecraft launched on its journey to Pluto – 2006
Jan 27: Apollo 1 astronauts Chaffee, White and Grissom die in fire in capsule – 1967
Jan 28: Seven astronauts killed when Space Shuttle Challenger explodes during launch – 1986
