Asterism astronomy - Open clusters

In astronomy, an asterism is a pattern of stars seen in Earth's sky which is not an official constellation. Like constellations, they are composed of stars which, while they are in the same general direction, are not physically related, often being at significantly different distances from Earth. An asterism may be composed of stars from one or more constellations. Their mostly simple shapes and few stars make these patterns easy to identify and thus particularly useful to those just learning to orient themselves when viewing the nigh ...

Including:

• Asterism astronomy - Background
• Asterism astronomy - Large seasonal asterisms
• Asterism astronomy - Other examples
• Asterism astronomy - Former asterisms
• Asterism astronomy - Open clusters

Read more here: » Asterism astronomy: Encyclopedia - Asterism astronomy

Undoubtedly, the best-known asterism is the Big Dipper. Composed of the seven brightest stars in Ursa Major where they delineate the Bear's hindquarters and exaggerated tail, the Dipper is often the first grouping of stars shown to beginners in the Northern Hemisphere. With its even more ridiculously lengthened tail, Ursa Minor hardly appears bearlike at all. It does much better under its pseudonym of the Little Dipper. Ursa Minor is not the only constellation that does not look very much like what it represents. ...

See also:

Asterism astronomy, Asterism astronomy - Background, Asterism astronomy - Large seasonal asterisms, Asterism astronomy - Other examples, Asterism astronomy - Former asterisms, Asterism astronomy - Open clusters

Read more here: » Asterism astronomy: Encyclopedia II - Asterism astronomy - Other examples

The visible stars are located at random in the sky. Even before the dawn of civilization, it became common to clump various stars together in connect-the-dots stick-figure patterns. The grouping of stars into constellations is essentially arbitrary, and different cultures have had different constellations, although a few of the more obvious ones tend to recur frequently, e.g., Orion and Scorpius. Historically, without an "official" list, there was really no difference between a constellation and an asterism. Anyone could arrange and name a grouping which might or might not be generally accepted. Still, some of our own constel ...

See also:

Asterism astronomy, Asterism astronomy - Background, Asterism astronomy - Large seasonal asterisms, Asterism astronomy - Other examples, Asterism astronomy - Former asterisms, Asterism astronomy - Open clusters

Read more here: » Asterism astronomy: Encyclopedia II - Asterism astronomy - Background

Argo is a special case. By far the largest of Ptolemy's constellations was Argo Navis (the ship Argo). Starting with Lacaille in his Coelum Australe Stelliferum (1763), it was common to refer to its various parts as the Keel, the Poop, and the Sails. In the 1930 IAU arrangement, Argo was deemed too large, and these asterisms were recognized as official constellations (Carina, Puppis, and Vela) the ...

See also:

Asterism astronomy, Asterism astronomy - Background, Asterism astronomy - Large seasonal asterisms, Asterism astronomy - Other examples, Asterism astronomy - Former asterisms, Asterism astronomy - Open clusters

Read more here: » Asterism astronomy: Encyclopedia II - Asterism astronomy - Former asterisms