Massive Star Forming Region DR21 in Infrared . ... JPL , Caltech , NASA Explanation: Deep in the normally hidden recesses of giant molecular cloud DR21, a stellar nursery has been found creating some of the most massive stars yet recorded. The orbiting Spitzer Space Telescope 's Infrared Array Camera opened the window into the cloud last year in mid- infrared light. The cloud is opaque to visible light because of dense interstellar dust . ... NASA Official: Jay Norris. ...