Perhaps surprisingly, there are no bright nebulae in Canis Major; there are a number nearby, however, in Canis Major's northerly neighbor Monoceros, and in Orion to the northwest. The chance positioning of these gas clouds happened to place them outside the boundaries of Canis Major, perhaps the universe's way of compensating for the Great Dog getting the brightest star in the sky. If so, that would make the nebulae given to the other star groups a sort of "constellation prize". OK OK, I couldn't resist.