Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Recorded in November 1997 with the Wide Field and Planetary Camera 2 onboard the Hubble Space Telescope, the picture is a closeup of a supernova remnant known as the Cygnus Loop . The nearly edge-on view shows a small portion of the immense shock front moving toward the top of the frame at about 170 kilometers per second while glowing in light emitted by atoms of excited Hydrogen gas. Not just another pretty picture, this particular image has provided some dramatic scientific results . In 1999, researchers used it to substantially revise downward widely accepted estimates of distance and age for this classic supernova remnant .
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