The eight April constellations include such popular groups as Hydra, the sea serpent, Leo, the lion, and Ursa Major, the great bear. Ursa Major is a large constellation that includes what may be the most famous constellation in the sky, the Big Dipper. The April sky contains a number of fascinating Messier objects including a large number of galaxies, both spiral and irregular. Leo contains five galaxies and Ursa Major contains five as well. Ursa Major is also home to the famous Owl Nebula, a planetary nebula formed when an old star ejected large amounts of mater into space. Click on any constellation below for more information.