Constellations and Legends

Constellations and Asterisms

Constellations are groups of stars which have been designated as representing a particular figure in the sky. Different cultures have done this in different ways, and many ancient and modern constellations are no longer in use. Eighty-eight of the traditional and modern Western constellations have been designated as "official" constellations by the IAU (the International Astronomical Union).

Constellations can be represented by stick figures, some of which are traditional, and others which are created by the illustrator of one book or another. In the past, constellations were usually depicted by artistic drawings based on allegorical figures, and different books typically had different drawings, which didn't always include exactly the same stars. In 1930, the IAU defined constellation boundaries which enclose the regions traditionally occupied by allegorical figures, so that every part of the sky is inside some constellation, or another. Stars which are inside the boundary of a constellation are usually said to be "in" that constellation, meaning that they are in a direction enclosed by that boundary.

Asterisms are groups of stars, such as the Little Dipper, Big Dipper, and the Pleiades, which are not constellations, but have well-known names of their own. The Big and Little Dippers are part of the Big and Little Bears. The Pleiades are an example of a cluster of stars, which happens to be visible to the eye, in the constellation of Taurus.

Дата добавления: 2015-09-04