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Hydra

The Sea Serpent

Abbreviation:Hya
Genitive:Hydrae
Origin:[antiquity]
Fully Visible:83°S – 54°N

Known as a serpent since Babylonian times, this is the largest constellation in terms of area. One Greek myth associates the water snake with a crow and a cup.

Older star atlases sometimes show a bird perched near the water snake's tail. Turdus Solitarius appeared first and was later replaced by Noctua. Neither of these constellations, nor the cat, Felis, lurking below the snake, survive today.

The constellation of Hydra

Notable Features

Visible Named Stars
α Hya Alphard This star sometimes appears as Cor Hydrae (from the Latin cor hydrae meaning 'the heart of the hydra') in older star atlases and catalogues.
ε Hya Ashlesha This is a multiple star system.
ι Hya Ukdah This K-type fourth-magnitude star has a high proper motion.
σ Hya Minchir This star sometimes appears as Minkalshuja in older star atlases and catalogues.
υ¹ Hya Zhang Zhang is derived from the name of a Chinese asterism consisting of this star, κ Hya, λ Hya, μ Hya, φ¹ Hya, and HD 87344.
HD 85951 Felis The name of this fifth-magnitude star is taken from the name of the obsolete constellation, Felis.
Other Interesting Stars
HAT‑P‑42 Lerna This twelfth-magnitude star is known to have at least one exoplanet and is located near the 'head' of the serpent.
Deep Sky Objects
M48 Although visible to the naked eye under perfect observing conditions, this open cluster is best viewed through binoculars.
M68 A telescope is necessary to spot this globular cluster.
M83 This is one of the closest and brightest barred spiral galaxies in the sky although it will required a large telescope to see any structure.
C59 Ghost of Jupiter A telescope will be needed to see this planetary nebula. It appears in the New General Catalogue as number 3242.
C66 William Herschel discovered this globular cluster, one of the oldest known in our galaxy, in 1784. It is also known as NGC 5694.
Meteor Shower Radiants
016 HYD σ Hydrids This minor shower is active during the first part of December, with a peak around 9 December. The parent body is currently unknown.