On the nights from January 24 to 26, look for the bright waxing gibbous Moon in the sky. It will stay inside the Winter Hexagon — one of the most famous asterisms in the Northern Hemisphere. In today’s article, we’ll tell you more about the Winter Hexagon and how to find it on the skydome. We’ll also reveal the difference between a constellation and an asterism.
What is the Winter Hexagon (Winter Circle)?
The Winter Hexagon or the Winter Circle is an asterism — a well-known group of stars — prominent in the Northern Hemisphere sky. This asterism is best visible in the Northern Hemisphere during winter and its shape reminds both a circle and a hexagon, although a hexagon is more accurate. This is why it’s called so.
The asterism is composed of seven luminous stars from six different constellations. They are:
- Rigel in Orion;
- Aldebaran in Taurus;
- Capella in Auriga;
- Procyon in Canis Minor;
- Castor and Pollux in Gemini;
- Sirius in Canis Major.
One more star lying toward the center of the asterism is Betelgeuse in Orion. The asterism covers an extensive area — about one-third of the skydome from the southernmost star in the Hexagon, Sirius, to the northernmost star, Capella.
The Winter Circle is mostly upon the Northern Hemisphere’s celestial sphere, adorns the sky from December to March, best visible around midnight. In the Southern Hemisphere, it can be seen in the evening in late February and early March; the asterism reaches its highest point in the sky at around 11 p.m. local time. It can appear as a summer hexagon in southern latitudes and can be extended with the bright star Canopus in the south.
The Moon inside the Winter Hexagon
The waxing gibbous Moon will be within the Winter Hexagon stars on January 24, 25, 26. Although our natural satellite will be more than 80% illuminated, all stars in the Winter Circle are first-magnitude, so you still should be able to see them despite the moonlight.
In January the Moon will cross the luminous Winter Circle for the first, but not the last time this year. The next closest passes will happen in February and March and then at the end of 2021, our natural satellite will come back inside the asterism. Due to the movement of the Moon and stars, the Moon will meet the Hexagon a little sooner every month.
How to find the stars of the Winter Circle?
Сonsult the stargazing guide Star Walk 2 to find the luminous pattern of stars. To make your search easier, change the appearance of constellations. Go to the app settings: in the “Constellations” section, choose the left one — this way, the alternative constellation images won’t interfere with your exploration. You can also lower the visual magnitude in the settings. Thus only the brightest stars will appear on the screen and the sky image in the app will look more like the sky above you.
Where is the Winter Triangle?
On January 24–26, if you look on the lower right from the Moon, you’ll find one more curious star pattern — the Winter Triangle. The Winter Triangle is a smaller asterism inside the Winter Hexagon. It’s formed by three prominent stars:
- Sirius in Canis Major;
- Procyon in Canis Minor;
- Betelgeuse in Orion (the Hexagon center).
What is the difference between a constellation and an asterism?
Constellations and asterisms are both patterns of stars. According to the list made by the International Astronomical Union in 1928, there are 88 official constellations. Former constellations and any other groups of stars are considered asterisms. Most constellations are very old. They’re the projection of how our ancestors saw groups of stars — as mythical creatures, beasts, warriors. On the other hand, asterisms are relatively new. They can contain stars from different constellations, like the Winter Circle, or be a part of one constellation. The most famous asterism is the Big Dipper that lies within the Ursa Major constellation.
Patterns you see in the sky above mostly depend on your imagination. We only make it easier for you to find the stars those patterns consist of. Share with us on social media if you managed to find the luminous stars of the Winter Circle.
Wishing you clear skies and happy stargazing!