The Rosette Nebula

The Rosette Nebula (also known as Caldwell 49) is located in the constellation of Monoceros (The Unicorn). It lies at a distance of 5,000 light-years from Earth and measure roughly 130 light years in diameter. The radiation from the young stars excites the atoms in the nebula, causing them to emit radiation themselves producing the emission nebula we see. The cluster of stars in the centre have been formed from material from the nebula itself.