When naming nebulae, astronomers often see peculiar shapes that most people don't. The horsehead and flame nebulae are an exception, however, because it is almost immediately recognisable at a glance where the flame and horsehead are. 

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The Flame and Horsehead Nebulae are star forming regions in the constellation of Orion, forming part of the much larger Orion Molecular Cloud Complex. The bright star in this image is Alnitak, and is one of the stars that comprise the belt of Orion. It is a massive star, emitting copious amounts of high energy radiation which ionises the gas clouds of the flame nebula, making it the powerhouse that lights the flame. On the other hand, the Horsehead Nebula is a dark nebula, which means that while it does not emit light on its own, it can still be seen as a silhoette against the the "curtain" of the background red emission nebula, IC 434.