(the "Water-bearer" or "Cup-bearer"), in astronomy, the eleventh sign of the zodiac, situated between Capricornus and Pisces. Its symbol is m, representing part of a stream of water, probably in allusion to the fact that when the sun is in this part of the heavens (January, February) the weather is rainy. It is also a constellation mentioned by Eudoxus (4th century B.e.) and Aratus (3rd century B.C.); Ptolemy catalogued forty-five stars, Tycho Brahe forty-one, Hevelius forty-seven. Aquarii is a well-defined binary, having both components of the fourth magnitude; it is probably of long period.