Our sky chart for the next few nights – January 8 and 9, 2020 – covers more area of sky than we typically show. It’s in answer to a reader in Nashville, who wrote:
I’ve heard mention of the Winter Circle of stars. Could you list the stars in this circle?
We can do better than that. We can advise you to go outside on this date, and look for the waxing gibbous moon, then notice the stars nearby. The moon is within the Winter Circle stars on this date. All the stars of the Winter Circle (sometimes called the Winter Hexagon) are first-magnitude stars, so they should be able to withstand tonight’s drenching moonlight.
This pattern of stars is not a constellation. It’s a lot of separate stars in different constellations. In other words, it’s what’s called an asterism. From our Northern Hemisphere locations, these same bright stars can be seen before dawn every late summer and early fall. And they can be seen in the evening every winter. Hence the name Winter Circle.
Are you familiar with the constellation Orion the Hunter? This brilliant constellation makes up the southwest corner of the Winter Circle. And Orion’s bright star Betelgeuse forms an equilateral triangle with the stars Sirius and Procyon, which we in the Northern Hemisphere call the Winter Triangle.
I wonder what these same stars are called in the Southern Hemisphere? They’re visible from there, but of course it’s summer there now. I don’t know if this particular collection of bright stars has some special name as seen from that part of the globe. If any of you do know … tell us in the comments!
Bottom line: The stars of the Winter Circle may be seen on these cold winter nights until well after midnight. On January 8, 2020, the moon is inside the Winter Circle.