Watch the Moon Cross Through a Winter Star Formation One Last Time
Last call on the winter hexagon.
You've probably seen the winter hexagon mentioned here before. It's not a one-time event. It's an asterism—a formation of stars that is not a constellation—that is visible throughout, as the name indicates, the winter.
It is no longer winter, however, and you're running out of chances to admire the formation of bright stars. Over the next handful of days, you'll be able to watch the moon cross through the winter hexagon. It's a convenient prompt to get out and do a little stargazing as the weather continues to get warmer, and we get back to meteor shower season. You'll see this take place from April 15-19, per Sky & Telescope.
The winter hexagon, sometimes called the winter circle, is comprised of six bright, easily identifiable stars. Over five nights, the moon will move from just outside one edge of the hexagon, into the asterism, and then out the other side.
The six first magnitude stars include the recognizable blue of Sirius, sitting at the bottom of the formation; Rigel, at the foot of Orion; bright Aldebaran; Capella; Pollux, one of Gemini's heads; and Procyon in Canis Minor. This group is sometimes mentioned with the star Castor, the other head inside the constellation Gemini. Castor isn't a first-magnitude star but is still quite bright. You can also spot the bright red star Betelgeuse in the middle of the hexagon, at Orion's shoulder. The six stars that form its corners are part of the constellations Orion, Taurus, Auriga, Gemini, Canis Major, and Canis Minor.
The winter hexagon isn't a tight grouping. The stars are spread out across the sky. You can get a sense of what it looks like from this graphic at EarthSky. You could also use a mobile app like SkyView to find your way to these stars.
Unfortunately, unlike you may have seen in December all the way through last month, the winter hexagon isn't high covering much of the sky. Still, it's a big, beautiful sight to see stretched across the sky. Plus, if you go out, you might catch a couple of meteors from the Lyrid meteor shower, which peaks later this month.