Hya

Hya is the standard astronomical abbreviation for Hydra, a southern celestial constellation. The name Hydra comes from the Hydra, a many-headed water-snake in Greek mythology. Hydra is one of the 88 modern constellations officially recognized by the International Astronomical Union. It was introduced in the 18th century by Nicolas-Louis de Lacaille and named after the mythological creature.

Geographically, Hydra lies in the southern celestial hemisphere and is notable for its large apparent size. It is the largest of the 88 constellations by area, covering about 1,300 square degrees. The constellation contains many faint stars as well as several deep-sky objects, making it relatively challenging to study with the naked eye but accessible to telescopes from appropriate latitudes.

Among its notable deep-sky objects is the planetary nebula NGC 3242, commonly known as the Ghost of Jupiter, which lies within Hydra. The region also hosts a number of distant galaxies and other nebulae that are of interest to professional and amateur observers.

In astronomical usage, Hya is the designated shorthand used in star catalogs and sky charts to indicate Hydra. The constellation’s long-standing association with the Hydra myth reflects the historical practice of naming southern constellations after creatures and figures from classical lore, a trend continued by Lacaille during his 18th-century survey of the southern sky.