Stockton Astronomical Society
Valley Skies - March 2000 Issue
Constellations:
Hydra - the Water Snake
Gen: Hydrae
Abb: Hya
Dec: +6.8° to -35.3°
RA: 8 hr 8 min to 14 hr 58 min
Area covered: 1,303 square degrees
Hydra is the longest constellation in our sky; it stretches about 100 degrees from Cancer in the west to Libra in the east. The constellation is so large that it takes over six hours for the whole constellation to rise above the horizon. You can find Hydra at its highest point in the sky at about 10:00 PM on the 1st of March.
Mythology
There are several myths associated with Hydra, some going as far back as 4000BC. During the early period of the Babylonian and Sumerian civilizations, Hydra was seen as the dragon goddess Tiamat. Tiamat was the chief foe of the god Marduk. Since Hydra at the time was at its highest point in the sky during the winter solstice they believed that Marduk (symbolized by the sun) would begin his rise in power until he defeated Tiamat and chased her over the horizon at the summer solstice. The constellation had the same story in Indian mythology, when it represented the monster Vritra, and was battled by Indra the sun god.
In Greek mythology the constellation has taken three major forms. One myth is of Hydra being the son of Typhon, the most dreaded of a group of giants that warred with the Olympian gods. It is also believed that Hydra may have been Typhon himself and that he chased the god down from Mount Olympus until Zeus was able to defeat him with thunderbolts.
When I wrote the article about Corvus, I told the story of Apollo and his crow. In this myth Corvus carried the water snake "Hydra" back to Apollo trying to get away with a lie about why he was late returning.
By far the most popular myth associated with Hydra is the one about Hydra being the multi-headed swamp serpent killed by Heracles. Killing the Hydra was one of the 12 labors of Heracles and it was definitely a major task. During the battle, every time he would cut off one head two heads would grow back in its place. The only way for Heracles to defeat the Hydra was to cut off a head then cauterize the stump with a torch before it was able to grow another head.
In the real world a Hydra is a very small aquatic animal approximately 3cm long that does regenerate parts of its body that have been cut off. This animal is classed as a hydrozoa and has reproductive organs of both male and female in one body.
Exploring in Hydra
I am going to hop to the first hit this month from the tail of last month's constellation (Monoceros). Use last month's chart to locate z (Zeta) Monocerotis, then hop 3° SSE to find NGC 2545 (M48). M48 is considered one of the missing Messier objects; it's location as logged by Messier is off by 5° but there are no other open clusters in the area that match his description. This cluster is very large and pretty rich with a tightly compressed central area shaped like an arrowhead. M48 is bright enough that you should be able to see it at the southern apex of an equilateral triangle formed by z, the tight grouping of 1, 2 & c Monocerotis and M48, in your finder scope.
From M48 hop 18° ESE to a (Alpha) Hydrae. Alpha is also known as Alphard, which comes from the Arabic and means "The Solitary One". This is the brightest star in Hydra at 2nd magnitude and is often the only star visible through the light pollution.
From Alphard travel just over 8° south to locate the 11th magnitude galaxy NGC 2811, a small but bright spiral galaxy that appears as an elongated smudge with a bright nucleus.
It's probably best to use your binoculars or finder scope to travel from NGC 2811, 8½° to n (nu) Hydrae then another 8½° ESE to m (mu) Hydrae. Once you locate m Hydrae hop just under 2° south to get to NGC 3242, "The Ghost of Jupiter". NGC 3242 is very bright at magnitude 7.7 and appears as a big green disk very close to the size of the planet Jupiter. Large scopes may be able to pick out the actual ring structure but my scope shows it as a uniform disk.
Our next hop will start at b (beta) Hydrae. Beta is the second brightest star in Hydra and I use the three bright stars on the West Side of Corvus to point the way. Once you locate and center Beta in your finder, hop 7° ENE to find the 8.9 magnitude spiral galaxy NGC 3621. This galaxy appears close to edge-on and has a small nucleus.
Return back to Beta then back to Corvus. This time use the two eastern stars to point you towards NGC 4590 (M68) located 3½° past Beta Corvus. M68 is a nice 8th magnitude globular cluster with a very tight center surrounded by 12th magnitude stars and one brighter star located to the southwest. This is the first globular cluster to look for this year, but there will be a lot more to come.
Our last object is a bit hard to locate. Start by moving from M68 to g (gamma) Hydrae, about 9½° to the northwest. From Gamma use binoculars and look to the southeast in the constellation of Centaurus for three stars in the head of the Centaur. These three stars form a triangle and are labeled K, G & I on my star chart. Use your binoculars or finder scope to sweep the area located two thirds of the way from Gamma to these three stars, looking for a very faint, fuzzy patch of light. This fuzzy patch in your scope is NGC 5236 (M83). M83 is a great face-on spiral galaxy, with what appears to be a strong central bar and heavily mottled arms. This galaxy is not classified as a barred spiral so it must be dark lanes that cause it to look this way. M83 is listed as 8th magnitude so it should be visible in most scopes at a dark site.
There are several other galaxies in Hydra but most are fainter than 12th magnitude, so you will need a rather large scope to find them.
Happy Star-Hopping...Eric
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Lasted Updated: 12/2/2000
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