Crater (constellation)

Lore & Background

In the Babylonian star catalogues dating from at least 1100 BC, the stars of Crater were possibly incorporated with those of the crow Corvus in the Babylonian Raven. British scientist John H. Rogers observed that the adjoining constellation Hydra signified Ningishzida, the god of the underworld in the Babylonian compendium MUL.APIN. He proposed that Corvus and Crater (along with Hydra) were death symbols and marked the gate to the underworld. Corvus and Crater also featured in the iconography of Mithraism, which is thought to have been of middle-eastern origin before spreading into Ancient Greece and Rome.

Crater is identified with a story from Greek mythology in which a crow or raven serves Apollo, and is sent to fetch water, but it delays its journey as it finds some figs and waits for them to ripen before eating them. Finally, it retrieves the water in a cup and takes back a water snake, blaming it for drinking the water. According to the myth, Apollo saw through the fraud, and angrily cast the crow, cup, and snake into the sky. The three constellations were arranged in such a way that the crow was prevented from drinking from the cup, and hence seen as a warning against sinning against the gods. Phylarchus wrote of a different origin for Crater. He told how the city of Eleusa near Troy was beset by plague. Its ruler Demophon consulted an oracle which decreed that a maiden should be sacrificed each year. Demophon declared that he would choose a maiden by lottery, but he did not include his own daughters. One nobleman, Mastusius, objected, forcing Demophon to sacrifice his daughter. Later, Mastusius killed Demophon's daughters and tricked the ruler in drinking a cup containing a mixture of their blood and wine. Upon finding out the deed, the king ordered Mastusius and the cup to be thrown into the sea. Crater signifies the cup.

In Chinese astronomy, the stars of Crater are located within the constellation of the Vermillion Bird of the South. They depict, along with some stars from Hydra, Yi, the Red Bird's wings. Yi also denotes the 27th lunar mansion. Alternatively, Yi depicts a heroic bowman; his bow composed of other stars in Hydra. In the Society Islands, Crater was recognized as a constellation called Moana-'ohu-noa-'ei-ha'a-moe-hara.

Reader's Guide

Crater is a small constellation covering 282.4 square degrees, ranking 53rd of the 88 constellations in area. It is bordered by Leo and Virgo to the north, Corvus to the east, Hydra to the south and west, and Sextans to the northwest. Its three-letter abbreviation, adopted by the International Astronomical Union in 1922, is 'Crt'. The official constellation boundaries, set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of six segments. In the equatorial coordinate system, the right ascension coordinates of these borders lie between 10h 51m 14s and 11h 56m 24s, while the declination coordinates are between −6.66° and −25.20°. Its position in the southern celestial hemisphere means that the whole constellation is visible to observers south of 65°N. The German cartographer Johann Bayer used the Greek letters alpha through lambda to label the most prominent stars in the constellation. Bode added more, though only Psi Crateris remains in use. John Flamsteed gave 31 stars in Crater and the segment of Hydra immediately below Crater Flamsteed designations, naming the resulting constellation Hydra et Crater. Most of these stars lie in Hydra. The three brightest stars—Delta, Alpha, and Gamma Crateris—form a triangle located near the brighter star Nu Hydrae in Hydra. Within the constellation's borders, there are 33 stars brighter than or equal to apparent magnitude 6.5. Seven star systems have been found to host planets. A few notable galaxies, including Crater 2 and NGC 3981, and a famous quasar lie within the borders of the constellation.

Did You Know?

• Crater is one of the 48 constellations listed by the second-century astronomer Ptolemy.
• Its two brightest stars, Delta and Alpha Crateris, are ageing orange giant stars that are cooler and larger than the Sun.
• Beta Crateris is a binary star system composed of a white giant star and a white dwarf.