Pisces Australis

Piscis Austrinus is already described, in its own article, as the parent of the zodiac's two fishes and as drinking the water poured from Aquarius's jar. That drinking posture is not an isolated image: it sits inside a much larger old reading of this entire quarter of sky as a sea.

The cluster running from Aquarius and Capricornus through Piscis Austrinus, Eridanus, Delphinus, Equuleus and the ship Argo shares no boundary and no single myth, only a persistent watery theme that predates Greek astronomy. Babylonian sky-lore, inherited by the Greeks along with the zodiac itself, already read this stretch as a sea, because the Sun crossed it during Mesopotamia's rainy season; Piscis Austrinus's fish, drinking from the jar beside it, is a natural extension of a reading that was already there before either figure had a name.

Modern historians of astronomy label the loose cluster the Heavenly Waters, a convenience term rather than a boundary Ptolemy drew, since his own forty-eight were sorted only into zodiacal, northern and southern lists.

Fomalhaut, the constellation's one bright star and by far the most prominent point of light in this whole watery region, makes Piscis Austrinus the most visible single member of the ancient sea's cluster of otherwise faint figures, a bright mouth in a mostly dim quarter of sky.

Piscis Austrinus, the Southern Fish, here named Pisces Australis, is a southern constellation, one of Ptolemy's forty-eight, depicting a fish drinking the water poured out by the neighbouring Aquarius, the water-bearer. It is dominated by Fomalhaut, a bright first-magnitude star that stands rather alone in a dim region of the autumn sky and so is sometimes called the Lonely Star of Autumn; its Arabic name means the mouth of the fish. The constellation is regarded as the parent of the two zodiacal Fishes of Pisces, said to be its offspring. In astronomical tradition it is a pattern of stars rather than a zodiac sign. These are the features of Piscis Austrinus as the classical and modern traditions describe it, distinct from any astrological reading; Fomalhaut is one of the more notable stars of the southern autumn sky.

Piscis Austrinus lies near several of Lacaille's eighteenth-century southern constellations, Grus the crane and Microscopium among them, part of the same eighteenth-century programme that filled the deep southern sky, invisible from the Mediterranean world where the Ptolemaic forty-eight were first catalogued, with a mix of exotic birds and scientific instruments. Grus, the crane, and Microscopium, both introduced well after Ptolemy, fill much of the surrounding southern sky in a similarly instrument- and creature-themed eighteenth-century style.