Astronomy Picture of the Day . Rungs of the Red Rectangle . ... T. Gull ( GSFC ), ESA , NASA Explanation: A distinctive X-shape and ladder-like rungs appear in this Hubble Space Telescope image of the intriguing Red Rectangle Nebula . The dusty cosmic cloud was originally identified as a strong source of infrared radiation and is now believed to contain icy dust grains and hydrocarbon molecules formed in the cool outflow from an aging central star. ... The Trifid Nebula in Stars and Dust . ...