Bright and Dark

Bright clouds of gas intermingle with dark clouds of dust in this image of IC 5146, the Cocoon Nebula. Both regions are giving birth to new stars. The bright regions are energized by hot young stars, while the dark regions have not yet given birth to stars capable of lighting them up. The bright regions appear to lie several hundred light-years closer than the darker ones. [Adam Block/Mount Lemmon SkyCenter/University of Arizona]