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Socrates, 469 - 399 BC

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Hydra

The Water Snake

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Hydra - Celestial Atlas by Alexander Jamieson - 1822

You've got the teeth of a Hydra upon you
You're dirty sweet and you're my girl.
T. Rex - Bang A Gong(Get It On) - 1971

Hydra is the largest and longest constellation in the sky. It stretches fully one quarter of the way around the horizon, and takes up two full pages of Alexander Jamieson's 1822 Celestial Atlas. Although the celestial Hydra has only one head, its mythological namesake apparently had many, as well as poisonous breath and blood. It guarded one of the entrances to the underworld, and the killing of this fearsome creature was the second of the twelve labours of Hercules. At first Hercules had trouble dealing with the monster, because every time he chopped off a head, two more would grow in its place. Hercules finally discovered that burning the stump of a severed head would stop it from growing again, and he defeated the monster. The gods placed it in the sky to commemorate his victory.

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Hydra - May 1, 10:00 PM - Latitude 35° North, Longitude 95° West





Stars of Hydra


The stars of Hydra look unremarkable at first, but if you spend a few moments gazing just above the southern horizon on a balmy spring night, you will sooner or later make out the long, meandering form of the snake, with the crow and the goblet on its back, and you will never see that part of the night sky the same again.

Alphard (RA: 09h27m35.229s DE:-0839'30.47")

The alpha star in the constellation Hydra is Alphard, which means the solitary one, because it is indeed the only bright star in that region of the sky. It is also known as Cor Hydrae, the heart of the Hydra. It is a K3III orange giant with a magnitude of 2.0, about 177 light years away.

Alkes and Kraz In Becvar

Although Hydra borrows the stars Alkes and Kraz In Becvar from Crater and Corvus, they are technically outside the boundaries of Hydra.

Al Sharasif - The Ribs

According to Richard Allen's Star Names, the brighter stars between Alphard and the Crater were collectively known to the ancients as Al Sharasif, The Ribs.

Al Minliar Al Shuja (RA: 08h38m45.419s DE:+0320'28.93")

The only other named star in the constellation is the dim, 4.5 magnitude Al Minliar Al Shuja, which means, the nose of the snake. It is a K2III orange giant, a distant 370 light years away.

TW Hydrae (RA: 11h01m 52.99s DE:-3442'24.77")

A faint little K6V orange main sequence star designated TW Hydrae is of great interest to astronomers because at a distance of 176 light years it is the closest T Tauri star to our solar system. T Tauri stars are young stars that have not yet achieved nuclear fusion, and shine solely from the energy of gravity and the friction of colliding particles. They are stars in their formative years, still drawing in matter from the accretion disks that surround them, also known as protoplanetary disks. The disk around TW Hydrae has a gap about the same distance from the star as Earth is from the Sun, suggesting the possible formation of an Earth-like planet.

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TW Hydrae - T Tauri Star With Protoplanetary Disk - European Southern Observatory - March, 2016

Planets of Hydra

HD 122430 (RA: 14h02m22.745s DE:-2725'47.24")

Hydra has no less than 16 stars that have confirmed planetary systems, but only one of these stars is visible with the naked eye, and you'll need a good dark night to see it. The star is HD 122430, near the tail of the snake, a K2III orange giant with a magnitude of 5.47. It has a planet almost four times larger than Jupiter, orbiting its star every 345 days at about the same distance Earth orbits the Sun. The system is quite far away at a distance of 440 light years.

Gliese 433 (RA: 11h35m 26.9s DE:-3232'23.9")

Very much closer at a scant 30 light years away, yet well beyond visual range at magnitude 9.81, is Gliese 433. It is an M1V red main sequence star, with a super earth only 5.3 times larger than our home planet. The bad news is the planet is in a tight seven day orbit only 5.4 million miles from its star, which would make it exceedingly hostile to any kind of life as we know it.

For more information on these and other extrasolar planets, visit NASA's New Worlds Atlas, and The Open Exoplanets Catalogue.



Deep Skies of Hydra

M48 - NGC 2548 (RA: 08h13m 42.0s DE:-0545'00")

M48 (NGC 2548) is an open star cluster located about 2,000 light years away. With a magnitude of 5.8, the cluster contains about 80 stars, estimated to be 300 million years old.

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M48 - Open Star Cluster - 2MASS/UMass/IPAC-Caltech/NASA/NSF - 1997-2001

M68 - NGC 4590 (RA: 12h39m 30.0s DE:-2645'00")

Globular star cluster M68 (NGC 4590) is 33,000 light years away with a magnitude of 7.3.

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M68 - Globular Star Cluster - Hubble Space Telescope - July, 2012

NGC 5694 (RA: 14h39m 36.0s DE:-2632'00")

Globular cluster NGC 5694 is very much farther away at a distance of 105,000 light years, and very much dimmer with a magnitude of 10.2. It is one of the most remote globular clusters in our galaxy. It is also one of the smallest, containing only about 100,000 stars. The cluster's most unique feature is that it is leaving our galaxy and heading off into intergalactic space, moving at the unusually high velocity of 614,250 mph (982,800 kph), well beyond the escape velocity of the galaxy.

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NGC 5694 - Globular Cluster - Google Sky Map

NGC 3242 - The Ghost of Jupiter (RA: 10h24m 48.0s DE:-1839'00")

Coming in at magnitude 8.6 is NGC 3242, known as The Ghost of Jupiter, for its Jovian-like appearance in a small scope. The Hubble Space Telescope reveals its true nature as a dying star - clearly visible in the centre of the image - shedding its outer layers as it runs out of fuel and slowly cools. The nebula is 1,400 light years away.

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NGC 3242 - The Ghost of Jupiter - Planetary Nebula - Hubble/ESA

Abell 33 (RA: 09h49m 4.14s DE:-250'22.55")

Much farther and much dimmer is the ejected gas cloud of another dying star, Abell 33. At a distance of 2,700 light years and a magnitude of 13.4. it is in the realm of large telescopes. The bright star on the lower right giving the nebula a diamond ring effect is seventh magnitude HD 83535.

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Abell 33 - Planetary Nebula - European Southern Observatory - April, 2014

ESO 378-1 (RA: 11h26m 43.95s DE:-3422'14.9")

Farther away still is yet another ghostly cloud of gas surrounding a dying star, ESO 378-1. It is 3,500 light years away with a very faint magnitude of 17.4.

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ESO 378-1 (PN K1-22) - Planetary Nebula - European Southern Observatory - August, 2015

M83 - The Southern Pinwheel Galaxy (RA: 13h37m00.0s DE:-2952'00")

Moving outside our own galaxy there is at least one other galaxy in reach of amateur scopes, M83 (NGC 5236), the Southern Pinwheel Galaxy, one of the closest and brightest spiral galaxies in the southern sky. It is only 10 million light years away, quite close as galaxies go, giving it an apparent magnitude of 7.54. Like our Milky Way, it is a barred spiral galaxy, but less than half the size with a diameter of 40,000 light years.

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M83 - The Southern Pinwheel Galaxy - European Southern Observatory, Chile - December, 2009

NGC 3621 (RA: 11h18m 18.0s DE:-3249'00")

More than twice as far away at 22 million light years is spiral galaxy NGC 3621. At magnitude 9.7 it is a challenge for smaller scopes.

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NGC 3621 - Spiral Galaxy - European Southern Observatory - November, 2011

NGC 3081 (RA: 09h59m 30.0s DE:-2250'00")

Jumping way out to 107 million light years and firmly into the realm of large telescopes we find NGC 3081. With its distinctive bright core and outer loop, it has a magnitude of 12.5.

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NGC 3081 - Spiral Galaxy - Hubble Space Telescope - June, 2014

NGC 3314 (RA: 10h37m 12.0s DE:-2741'00")

At 117 million light years we come across NGC 3314, with a magnitude of 14.0. It is two overlapping galaxies that appear to be colliding, but are actually very far apart. NGC 3314a is in front, 117 million light years from us, and NGC 3314b is in a direct line of sight behind it, about 23 million light years farther away.

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NGC 3314 - Hubble Space Telescope - June, 2012

ESO 510-13 (RA: 13h55m 4.16s DE:-2646'46.48")

Finally, out at the very great distance of 150 million light years, at magnitude 13.4, is the unusual spiral galaxy ESO 510-13, with its highly warped dust lane.

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ESO 510-13 - Spiral Galaxy - European Southern Observatory - April, 1999







Winter: Orion   Canis Major   Canis Minor   Monoceros   Lepus   Eridanus   Taurus   Auriga   Camelopardalis   Lynx   Gemini   Cancer  
Spring: Hydra   Sextans   Crater   Corvus   Leo   Leo Minor   Ursa Major   Ursa Minor   Canes Venatici   Coma Berenices   Virgo   Bootes  
Summer: Draco   Corona Borealis   Hercules   Ophiuchus   Serpens   Libra   Scorpius   Sagittarius   Scutum   Aquila   Sagitta   Vulpecula   Lyra   Cygnus  
Autumn: Andromeda   Perseus   Pegasus   Cassiopeia   Cepheus   Cetus   Lacerta   Delphinus   Equuleus   Capricornus   Aquarius   Pisces   Aries   Triangulum  
Southern Skies: Centaurus   Crux   Lupus   Corona Australis   Piscis Australis   Sculptor   Tucana   Fornax   Dorado   Columba   Puppis   Carina   Vela  


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