The Horsehead Nebula (B33) is a dark cloud of dust and gas silhouetted against the bright emission nebula of IC434.  It is located near the eastern most star of Orion's belt at a distance of approximately 1600 light years.  The nebula gets its name from its resemblance to the chess knight.  The Horsehead is a very difficult object to view visually even in large telescopes; however, long duration exposures such as the one above reveal its intricate structure.