When we look at the night sky we see stars and groups of stars. Some of these groups are among the 88 official constellations. Like Orion, Hercules, Ursa Major, etc. For a list of the official constellations look here). But some of the best known star groups aren't actually constellations! Some are even better known than the official constellations. These unofficial groups are called asterisms. And some of these are better known than the official constellations.
Teaching the sky
Cubs learning the sky for their Astronomer badge will learn some asterisms as a way to identify the 5 constellations they need. Listed below are a few of the most common I teach to our cubs. I've listed them by by season assuming you'll be looking just after twilight.
All year (circumpolar):
- The Summer Triangle (Cygnus, Lyra, Aquila): June-November
- The Keystone (Hercules): April-September
- The Teapot (Sagittarius): July-September
- The Sickle (Leo): July-January
- Orion's Belt and Orion's Sword (Orion): November-April
- The Kids (Auriga): September-May
There are also binocular and telescopic asterisms. One of the most famous and striking is called the Coat hanger (Brocchi's Cluster). The Coat hanger can be spotted by eye but needs binoculars to see its pattern. It can be found not far from the western edge of the Summer Triangle moving from Vega in Lyra to Altair in Aquila just past Alberio.
In addition to the Wikipedia article, there are a many sites with lists of asterisms.
- SEDS (Students for the Exploration and Development of Space) has a list here.
- Sofware Bisque (The Sky) have a good list of binocular and scope asterisms here.
So, what's your favorite asterism?
I wanted to write an article on asterims for Cubs, Scouts and beginners and had expected to find longer online lists of asterisms than were at Wikipedia and SEDS. I also have very little information on southern hemisphere asterisms.
Do you know any that aren't on these lists? Do you have a favorite?
Please let me know via comment or email.