Just as the Summer Triangle is a useful heavenly landmark for locating stars, constellations and objects of interest in the summer night sky, so too is its winter equivalent, known as the Winter Triangle.
One thing to bear in mind, though, is that both astronomical arrangements are not constellation in their own right, but are in fact examples of asterisms, or collections of stars grouped together to form patterns that are easier to spot than many of the 88 recognized constellations. Furthermore, an asterism may either include some of the stars of just one constellation, such as the Big Dipper, or several stars from different constellations, such as the Winter Triangle.
The Winter Triangle
The Winter Triangle is made up of three stars belonging to three individual constellations, namely Betelgeuse in Orion, Sirius in Canis Major, and Procyon in Canis Minor:
–Betelgeuse in the constellation of Orion is a reddish-orange star depicting one of the giant’s shoulders, and is the 9th brightest star in the night sky. This supergiant star has around 20 times the mass of our sun, and is found 650 light years from the Earth.
–Sirius in Orion is the brightest star in the entire sky, and is located at the Winter Triangle’s southernmost tip. It is white in color, although its hue may change as it twinkles low in the winter night sky. Is has around twice the mass of our sun, and is only 8.6 light years distant.
–Procyon in Canis Minor is a yellowish-white star that is the 8th brightest in the celestial heavens. It is located around 11.4 light years away, and has around 1.5 times the solar mass.
Together these three bright stars form one of the most recognizable patterns in the winter sky, and adding to their splendor is the fact that on a dark moonless night the Milky Way can be seen passing through the Winter Triangle, and extending beyond the constellation of Taurus before stretching away into the northwestern sky.
The Winter Hexagon
Interestingly, two of the stars in the Winter Triangle, namely Sirius and Procyon, form part of an even bigger asterism of stars called the Winter Hexagon or Winter Circle. This prominent winter asterism comprises six stars, with the additional stars including Rigel in Orion; Aldebaran in Taurus; Capella in Auriga; and Pollux in Gemini.
In the northern hemisphere, the Winter Hexagon can be seen high in the night sky from December to March, while from the southern hemisphere it can be observed in February and March.