Monoceros constellation. Optical image of the constellation of Monoceros (the Unicorn). This faint constellation is situated between Orion the Hunter and Canis Minor. Monoceros is not an ancient constellation and there are no definite legends attached to it. The best known feature in Monoceros is the Rosette Nebula seen as a small, round and pink area (upper right). This is a cloud of interstellar gas, mainly hydrogen, lit up and ionised by young and hot stars embedded in it.