Shock waves in gas and dust

The Spitzer Space Telescope, launched in 2003 with its Infrared Array Camera (IRAC), is the largest infrared telescope ever sent into space. Its instruments give scientists the ability to peer into regions of space invisible to optical telescopes, including dusty stellar incubators, the centers of galaxies, and growing planetary systems, NASA says.

The telescope was originally launched with a supply of liquid helium coolant for its camera because the heat it gave off could interfere with infrared light given off by the warm objects it was observing. As expected the coolant slowly depleted and ran out in 2009, or about 1,000 days ago, but the IRAC can still take images, although without all its infrared sensors.

In this slideshow, we've put together a sampling of photos from the past 1,000 days.

Nicknamed the "Tornado" nebula, light emitted from a shocked molecular hydrogen, visible here in green, is believed to be caused by an outflowing jet of material from a young star that has generated shock waves in surrounding gas and dust.