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. Hydra has only one readily identified star alpha or Alphard which marks the heart of the snake. Hydra is usually identified with the multi headed creature that was slain by Hercules.