The winter sky has some brightly lit star patterns visible this month, including a triangle featuring Mars at one of its points, making it worthwhile to brave the winter temperatures for stargazing.
These shapes aren’t constellations, but asterisms : groups of stars that form recognizable patterns but that don’t have official locations from the International Astronomical Union. The Big and Little Dippers are asterisms, for example, though their stars are part of the constellations Ursa Major and Ursa Minor.
The Winter Triangle, which is especially visible now, is made up of the stars Sirius, Procyon, and Betelgeuse, which are found within the constellations Canis Major, Canis Minor, and Orion, respectively. And the asterism is part of an even larger asterism known as the the Winter Circle (or Winter Hexagon) , which is also visible in the winter sky from December to mid-April.
For the next few weeks (until about mid-March), there’s another triangle lighting up the night. The “Mars Triangle” is an even less official shape—not technically an actual asterism—with the name merely a suggestion by Space.com . If you connect Mars with Pollux and Castor, both from the constellation Gemini, you get smaller isosceles triangle, with the Red Planet as the brightest of the three points. This triangle will slowly shift as Mars moves relative to the fixed stars until they are all in a straight line in early April. Unlike asterisms, the so-called Mars Triangle is temporary and in flux.
Where (and when) to look for the Winter and Mars Triangles
The Winter Triangle is visible in the Northern Hemisphere now through the rest of this month. Look high in the southeast sky, near Orion’s belt , after sunset. Sirius, the brightest of the three stars, will appear first, followed by Procyon and Betelgeuse. The triangle is visible until the early morning hours, when it will set toward the west-southwest. (The Winter Triangle appears in the Southern Hemisphere between May and August.)
To see the Mars Triangle, Space.com suggests looking east around 6:30 p.m. local time. Mars is the brightest point and currently the vertex of the triangle, with Castor and Pollux making up the base. The triangle will be visible until about mid-March, though again, the shape will shift significantly between now and then.
The Winter Circle , which includes Sirius and Procyon (from the Winter Triangle), Castor and Pollux (from the Mars Triangle), as well as Rigel, Capella, and Aldebaran, rises in the east and sets in the west throughout the winter.
