Horsehead Nebula

One of the most recognisable shapes in the night sky, Barnard 33 is a dark nebula in Orion silhouetted against the bright emission nebula IC 434 behind it, approximately 1,375 light-years away. The horse-head shape is a dense pillar of cold gas and dust slowly being eroded by ultraviolet radiation from the nearby hot star Sigma Orionis. New stars are forming deep within its dark interior, hidden from optical telescopes.