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April 9, 2011

Most of the constellations of the ancient world are bright and prominent -- patterns like the scorpion of Scorpius, the lion of Leo, and Orion's mighty hunter. But a few are feeble little things. Under today's light-polluted skies, it taxes the eyes to find them, and the brain to "see" them as the figures they're supposed to represent.

A good example is Crater, the cup. It's well up in the southeast as darkness falls, and rolls across the southern sky as the night progresses. It represents a cup that nearby Corvus, the crow, brought to the god Apollo. Various tales say that the cup contained either water or wine.

And in fact, when you look at a diagram of the constellation, with lines connecting the stellar dots, eight of its stars do form the outline of a chalice. But that diagram doesn't translate very well to the actual sky. From most cities and towns, it's tough to see any kind of pattern in that part of the sky.

In fact, it's tough to see any of the stars at all. Only one rates brighter than fourth magnitude, which is a fairly good cut-off line for seeing stars from modestly light-polluted suburbs. It doesn't have a proper name; it's known only by its Greek-letter designation, Delta Crateris. It's about 200 light-years away.

All of the other stars of Crater are fainter, so you need clear, dark skies to see them -- and a good starchart to piece together the faint celestial cup.

We'll have more about the cup tomorrow.

Script by Damond Benningfield, Copyright 2011


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