A little ramble through Hydra the Water Snake

Hydra is the largest constellation in the sky but is by no means easy to find on account of its faintness. Hydra winds its way from the head in the northern hemisphere on the borders of Cancer to the tip of its tail south of the celestial equator near Libra and Centaurus.

There is a suggestion that Hydra it is part of the story of Jason and the Argonauts in that it represented the Dragon of Aetes helping to guard the golden fleece. The Hydra would be destroyed by Hercules.

It is possible that the Hydra was the snake depicted on a uranographic stone from the Euphrates dating to about 1200 BCE.

The Arab astronomer Al Sufi thought that the constellation was Al H’ail the Horse and was formed of stars that are now in Hydra but some also from Leo and Sextans

The Egyptians considered it the sky representative of the river Nile and gave it their name for the river.

Hydra has only one bright star Alphard which comes from the Arabic Al Fard al Shuja which means the Solitary One in the Serpent. Another Arabic name for Alphard was Al Fakar al Shuja which means the Backbone of the Serpent.

Tycho the last of the great pre telescopic astronomers called the star Cor Hydrae or the Hydra’s Heart in the 1590s.

Alphard is a magnitude 2.0 star the same brightness as the North Star but because it is not as high as the north Star it does not seem as bright. Alphard is 177 light years and is a K class star making it cooler than the Sun.

There are three Messier objects in Hydra.

Messier 48

An open cluster discovered by Messier in 1771 there is some confusion with M48 because the position given by Messier was not where M48 actually is. In 1783 Caroline Herschel, sister of William Herschel identified it, but the credit still goes to Messier. Sir John Herschel Caroline’s nephew described it “a superb cluster which fills the whole field; stars of 9th and 10th to the 13th magnitude – and none below, but the whole ground of the sky on which it stands is singularly dotted over with infinitely minute points

 M48 is 2,500 light years away shines at mag 5.8 and contains around 450 stars. A ;pair of binoculars will be needed to see it. 

Messier 68

A globular cluster discovered in 1780 , William Herschel described it "a beautiful cluster of stars, extremely rich, and so compressed that most of the stars are blended together". Its magnitude is 9.7 and is 33,000 light years away. A small telescope will be needed to find M68 

Messier 83

The Southern Pinwheel Galaxy so named because it looks like M101 the Pinwheel Galaxy in Ursa Major, it was discovered in 1781, it had been seen earlier by Nicolas Loius de Lacaille in 1752 from the Cape of Good Hope. M83 lies at a distance of 15 million light years. M83 shines with a mag of 7.5. A small telescope will be needed to see it.

Six supernovae have been observed in M83: SN 1923A, SN 1945B, SN 1950B, SN 1957D, SN 1968L and SN 1983N.

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