- Hydra (constellation)
name = Hydra
abbreviation = Hya
genitive = Hydrae
symbology = the
RA = 8-15h
areatotal = 1303
arearank = 1st
numbermainstars = 17
numberbfstars = 75
numberstarsplanets = 6
numberbrightstars = 1
numbernearbystars = 2
starmagnitude = 1.98
stardistance = 31.1
numbermessierobjects = 3
meteorshowers =Alpha Hydrids
Canis Minor Centaurus
Monoceros Puppis Pyxis Sextans
latmax = 54
latmin = 83
month = April
Hydra (pronEng|ˈhaɪdrə) is the largest of the 88 modern
constellations, and was also one of the 48 constellations listed by Ptolemy.
Hydra is the largest modern constellation, at 1303 square degrees.Despite its size, Hydra contains only one reasonably bright
star, Alphard(α Hya, 30 Hya), which is of apparent magnitude1.98. Alphard("the solitary one") is actually a double star. The other main named star in Hydra is Sigma, σ, Hydrae, which also has the name of Minaruja, from the Arabicfor snake's nose. At magnitude 4.54, it is rather dim. R Hydraeis a Mira variablestar that ranges in magnitude between 3.5, when it can be visible to the naked eye, to 10.9, when a telescopeis required to see it.
There are several
double stars of interest in Hydra. Epsilon Hydrae(ε Hya) is a binary starwith components of magnitudes 3.3 and 6.8, separated by 2.7 arcseconds. N Hydrae(N Hya) is a pair of stars of magnitudes 5.8 and 5.9. Struve 1270(Σ1270) consists of a pair of stars, magnitudes 6.4 and 7.4.
The constellation also contains the radio source
Notable deep sky objects
The constellation Hydra contains three Messier objects. M83, also known as the Southern Pinwheel Galaxy, is located on the border of Hydra and
Centaurus, M68 is a globular clusternear M83, and M48 is an open star clusterin the western end of the serpent.
The constellation Hydra resembles a twisting
snake, and features as such in some Greek myths. In Greek mythology, a crowserves Apollo. It is sent to fetch water, but it rests lazily on the journey, and after finally obtaining the water in a cup, takes back a water snake as well, as an excuse. According to the myth, Apollo saw through the fraud, and angrily cast the crow, cup, and snake, into the sky. The origin of this story is likely to be the juxtaposition of this constellation with those of Crater, and Corvus, in the area of the sky known as the Sea.
The Hydra was also considered to be the
Lernaean Hydra(as defeated by Heraclesfor one of his Twelve Labours) by the Greeks. Its position in the sky (below the ecliptic), together with the constellation Cancer (which lies near its head) may be the origin of parts of the myth.
* Ian Ridpath and Wil Tirion (2007). "Stars and Planets Guide", Collins, London. ISBN 978-0007251209. Princeton University Press, Princeton. ISBN 978-0691135564.
* [http://www.allthesky.com/constellations/hydra/ The Deep Photographic Guide to the Constellations: Hydra]
* [http://www.ianridpath.com/startales/hydra.htm Star Tales – Hydra]
Wikimedia Foundation. 2010.