Dark nebula. Composite infrared image of the filamentary or snake-like dark cloud (G11.11-0.12) in a region of the Milky Way. Dark or absorption nebulae are clouds of cold dust and gas that appear dark because they block light from the stars beyond them. Infrared dark clouds also appear dark when surveyed in infrared because they lack emission of infrared wavelengths. This image was made as part of the Two Micron All Sky Survey (2MASS) project using ground-based telescopes in the USA and in Chile. The 2MASS project began in 1997 with the aim of surveying the entire sky using near-infrared technology.