The Big Bear is more than just the Big Dipper. The dipper outlines the body and tail of Ursa Major, the big bear. But the constellation covers much more territory. Some fainter stars outline the bear’s legs and head. But it’s the stars of the dipper that we most notice – not only because they’re fairly bright, but because they form an easy-to-see pattern.
The dipper is an “asterism” – a group of stars that forms a discernible pattern, but that doesn’t form a whole constellation. An asterism can be part of a constellation, as the dipper is, or it can incorporate stars from two or more constellations.
A couple of examples are in good view this evening. A small one is the Circlet of Pisces – five stars that outline the head of one of the fish of Pisces. The stars aren’t that bright, but they form a compact pattern, making the circlet easier to pick out. And it has a bright pointer: It’s close to the lower right of Venus, the “evening star.”
On the other end of the spectrum is the Winter Hexagon or Winter Circle. It is outlined by seven stars – most of them among the brightest in the night sky. The pattern spans more than six times the width of your fist held at arm’s length. It ranges from Sirius, the brightest star in the night sky, which is low in the southeast at nightfall, to yellow-orange Capella high in the east. It incorporates stars from six constellations – the largest of all the well-known asterisms.
Script by Damond Benningfield