Orion Nebula (M42), optical image. The Orion Nebula is a vast cloud of dust and gas where new stars are being formed. It is located around 1500 light years from Earth, in the constellation of Orion. It is estimated to be 24 light years across, with a mass of about 2000 times the mass of the Sun. Astronomers have directly observed protoplanetary disks, brown dwarfs, intense and turbulent motions of the gas, and the photoionizing effects of massive nearby stars in the nebula. Photographed in 2015, from Kustavi, Finland.