Sh2-278 is an emission nebula in the constellation Orion. It is observed in the western part of the constellation, about 3 ° west of the Orion Nebula and 3 ° NNE of the bright star Rigel, the brightest of Orion. It can be easily photographed through a medium power amateur telescope equipped with special filters, even if long poses are necessary. It is a fragment of the gas clouds that make up the molecular nebulous complex of Orion. Like the other peripheral clouds of the complex, this also shows signs of erosion due to the shock wave caused by the stellar wind of the shining stars of spectral class O and B belonging to the Orion OB1 association, which are also the source of ionization. Basically, the nebula is made up of two comet-like gas canopies, with the head facing the association and the dispersing canopy facing the opposite side. Part of the gas that makes up the cloud is not ionized, thus remaining dark, while other parts are instead illuminated but not ionized, thus shining by reflection.