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The Moon is wading through the "celestial sea" -- a group of constellations that are all related to water. Tonight, the Moon is at the eastern edge of Pisces, the fishes. To the west, look for Aquarius, the water bearer, and Capricornus, the sea goat. Three constellations form a southern tier of the sea: Eridanus, the river, which rises late; Cetus, the whale or sea monster, and Piscis Austrinus, the southern fish.
These constellations probably were associated with water because the Sun passed across them during the rainy season in the ancient Middle East.
The most prominent star in the group is Fomalhaut, which represents the mouth of Piscis Austrinus. It's in the south at nightfall, and it's easy to find because it's the only bright star in that whole region of the sky.
Fomalhaut is a young star -- it's still surrounded by the debris left over from its formation. That disk of material also contains a planet -- one of the few planets in other star systems that've been photographed. Hubble Space Telescope has taken a few snapshots of it, although it looks like nothing more than an orange dot.
The planet probably resembles the giant of our own solar system, Jupiter, which is passing through the sea right now. It's well to the upper right of the Moon at nightfall, along the border between Pisces and Aquarius. It outshines all the true stars in the night sky, so it's hard to miss -- a bright interloper floating in the celestial sea.
Script by Damond Benningfield, Copyright 2010