This asterism is a highlight of the winter sky

Greetings, Stargazers.

I have to say that comet 46P/Wirtanen last month exceeded my expectations. By that, I simply mean I could see it with my naked eye, even if it was just barely. Every month, there are probably half a dozen comets you could see dimly through a telescope, but ones you can see with your naked eye only come around every decade or so.

January is also the time that I like to at least mention one of my favorite asterisms, the winter hexagon. I reviewed it in more detail last year, but this hexagon is one that can help you learn eight stars in six different constellations.

Start by finding the three belt stars of Orion that are now prominent in the southeastern sky after dusk. Betelgeuse, the bright red star above and to the left of the three belt stars, is the center of the hexagon. Use a star chart or phone app to help you find the six points around the edge of the hexagon.

These will include Rigel, on the opposite side of the belt from Betelgeuse, and then, going counterclockwise, you can find Aldebaran, Capella, the twins Castor and Pollux, Procyon and then Sirius, the brightest star in the sky.

This is also a good season for binoculars. If you still have them out from looking for the comet, make sure to take a look at the Orion nebula. Situated between the belt stars at Orion’s waist and Rigel at Orion’s foot is a small grouping of what looks like three moderately dim stars. The grouping is most often referred to as Orion’s sword, but persistent ribald rumors suggest that sword is just a euphemism for Orion’s manly parts below his belt.

The center of this grouping is the Orion Nebula, or M42. It is one of the more interesting objects in the night sky, but not because of its strategic placement. It is one of the few nebulae visible to the naked eye.

M42 looks great in binoculars and is a favorite target for those with a small telescope. The wisps of nebulosity extend out far enough to fill the field of view through a low magnification eyepiece, and the central region is bright enough to be a favorite target at star parties.

With a slightly higher magnification, you can resolve the trapezium, a tight cluster of stars near the center of the nebula. Four stars are visible with small telescopes. With a larger telescope, challenge yourself to see if you can see more stars in the grouping.

The moon will be full this month on the same day its orbital path crosses the ecliptic (the path the sun follows). This means there is a total lunar eclipse this month. Assuming clear skies, you will be able to see it on the evening of Jan. 20. Expect some mainstream news and social media alerts about this event. Many will like to call it a supermoon because the full moon this month happens only a day before perigee. But even the super-est of moons can be covered with your index finger held at arm’s length.

Mars is still fairly bright in the evening sky, but no longer outshines the winter stars. It can be seen to the south after sunset and will set in the west shortly after 11 p.m.

For several mornings around Jan. 22, the two brightest things in the sky besides the sun and the moon will be within a couple of degrees of each other. Venus, at magnitude -4.3, and Jupiter, at magnitude -1.8, will both be rising a little after 4 a.m. Both planets are interesting with a little magnification. Venus will be in a half-moon phase, and the four Galilean moons of Jupiter will make a nice line along the plane of the ecliptic.

And don’t forget to see if you can find all eight stars in the winter hexagon.

Charles Hakes teaches in the physics and engineering department at Fort Lewis College and is the director of the Fort Lewis Observatory. Reach him at hakes_c@fortlewis.edu.