Largest of the 88 modern constellations. Measures 1303 degrees squared.Sometimes confused with the constellation Hydrus. Hydra is a greek constellation, but was originally Babylonian. Originates from the Lernaean Hydra that was slain by Heracles (Roman form: Hercules) as part of his 10 labors, but wasn’t counted since his nephew, Iolaus, helped him kill the Hydra by burning its neck when Heracles decapitated the Hydra’s nine heads. Commonly represented as a water serpent.In Chinese astronomy, the Hydra is located within the Vermilion Bird and the Azure dragon. In Japanese culture, the stars are known as Nuriko. The Hydra as one reasonably bright star, known as Alphard, designated as Alpha Hydrae. It is an Orange giant that is 2.0, 177 light years away from Earth. Beta Hydrae is a blue-white star of magnitude 4.3, 365 light-years from Earth. Gamma Hydrae is a yellow giant of magnitude 3.0, 132 light-years from Earth. Can be seen between 60 and 90 degrees latitude.Right ascension is 10 hours. Best seen in April at 9pm in the Northern hemisphere. The ghost of Jupiter in the Hydra Constellation is a planetary nebula. The Southern Pinwheel galaxy is the Hydra. Has an open star cluster called M48. Alphard has a temperature of 4000 kelvin ( 6740.33)Alphard is 40 times larger than the sun. 17 main stars in Hydra, with planets orbiting them. Hydra A is a black hole in Hydra.It is 200 times longer than the moon, making it the longest constellation.