Before you wonder, no, it isn’t a rollercoaster named Barnard, more of an arc really. But it ain’t no rollercoaster.
It is an emission nebula (A cloud of ionisied gases and emits light at various wavelengths) estimated to be either 500 light or over a 1000 light years away from the Solar System set in within the constellation of Orion, and is either 50 or 150 lightyears in radius. It is a rather unique gas cloud as it is part of the Orion Complex, which is a cloud group of other star-forming nebulae, most notably Orion, and other minor ones such as the Flame and Running Man. The dark Horsehead nebula is a part of it as well.