Hydra, spanning 1303 square degrees of the sky, is the largest constellation. Hydra is located in the skies of the southern hemisphere and was first named by the Greek astronomer Ptolemy in the second century.
Hydra is part of the Hercules family of constellations. Despite its large size, the constellation has very few prominent features. Alphard is a second magnitude star and the brightest object in the constellation. Hydra also contains two magnitude 3 yellow giant stars. The Southern Pinwheel Galaxy, which is one of the closest and brightest barred spiral galaxies in the sky, can be found situated between Hydra and Centaurus.