With a surface area of 1303 square degrees and a length of more than one hundred degrees, Hydra is the longest and largest of the 88 contemporary constellations. Its northern end borders Cancer, while its southern end borders Libra and Centaurus. (Ridpath & Tirion 2001) The astronomer Claudius Ptolemy included it in his list of 48 constellations from the second century. It crosses the celestial equator and is frequently portrayed as a water serpent.
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History and Mythology
The Babylonian constellation MUL.APIN has a "serpent" constellation (MUL.DINGIR.MUS) that roughly corresponds to the Greek constellation of Hydra. It is one of two constellations known as "serpents" in Babylonian mythology, the other being Serpens, the ancestor of the Greek Serpens. (White 2008) In some Greek mythology, the Hydra is shown as a snake that is twisting. According to one tradition, a crow used a water snake to serve Apollo in a cup as it was on its way to get water. When Apollo discovered the trick, he was furious and threw the crow, cup, and snake into the sky. A different constellation's representation of the monster Hydra, which Hercules slew and had many heads, is also connected to it. (Ridpath & Tirion 2001) If one of the Hydra's heads were removed, two more were said to grow in its place. Iolaus, Hercules' nephew, used fire to burn the necks to stop them from growing again, which allowed Hercules to defeat the Hydra. (Chen 2007) The star Ashlesha represents Hydra in Hindu mythology. The Vermilion Bird and the Azure Dragon contain the stars that makeup Hydra in Chinese astronomy. The collective name for the Hydra's head was "Min al Az'al," which is Arabic for "belonging to the desolate spot." |
Deep-sky Objects
Messier 83 (M83) – Pinwheel Galaxy - Barred Spiral Galaxy
Messier 68 (M68) – Globular Cluster
Messier 48 (M48) – Open Cluster
NGC 3242 – Planetary Nebula
NGC 5694 – Globular Cluster
NGC 3314 – pair of overlapping galaxies at different distances
Main stars - 17
Bayer stars - 75
Stars with planets - 18
Stars brighter than magnitude 3.00 - 2
Stars within 32Ly - 4
Bordering
constellations
Meteor showers
Messier 83 (M83) – Pinwheel Galaxy - Barred Spiral Galaxy
Messier 68 (M68) – Globular Cluster
Messier 48 (M48) – Open Cluster
NGC 3242 – Planetary Nebula
NGC 5694 – Globular Cluster
NGC 3314 – pair of overlapping galaxies at different distances
- NGC 3314a face on spiral galaxy
- NGC 3314b oblique spiral galaxy
Main stars - 17
Bayer stars - 75
Stars with planets - 18
Stars brighter than magnitude 3.00 - 2
Stars within 32Ly - 4
Bordering
constellations
- Antlia
- Cancer
- Canis Minor
- Centaurus
- Corvus
- Crater
- Leo
- Libra
- Lupus (corner)
- Monoceros
- Puppis
- Pyxis
- Sextans
- Virgo
Meteor showers
- Alpha Hydrids – peaks first week of January
- Sigma Hydrids – Peak in early December