IC5146, the Cocoon Nebula, is an emission nebula in Cygnus that lies at the end of B168, a large area of dust and hydrogen, not excited from stars. This dark nebula stop the light emitted from stars and nebulae, so probably the Cocoon is much larger than the area normally visible. Embedded into IC5146 is an open cluster containing about 20 stars that have the same catalog number of the Cocoon.