Easy Cache-N-Dash along East Greenland Rd
An asterism is a group of stars, usually inside a constellation, that may or may not be more famous than the constellation it is part of.
The Pleiades, or Seven Sisters, (or Subaru, or whatever), is an asterism of Taurus the Bull- its a swarm of bees stinging the bull on his back.
The Big Dipper is an asterism of Ursa Major, the Great Bear. The Big Dipper is her hindquartes and long, stretched-out tail. (And there are wonderful stories on how that bear got such a long tail, and her cub, the Little Dipper, too!)
The Northern Cross is an asterism for Cygnus the Swan.
A few asterisms are made up of more than one constellation. The Summer Triangle is made up of three stars from three constellations: Deneb from Cygnus the Swan, Altair from Aquila the Eagle, and Vega from Lyra.
So next time you hear someone talking about the Big-Dipper and calling it a constellation, just remember they are not seeing "'the whole picture"
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