Great Intergalactic Cobwebs
Posted: Friday, April 19, 2002
Much has been written about the first three minutes after the birth of the Universe in the Big Bang. But what do astronomers know about the next few billion years of our Universe's childhood?
Astronomers agree that matter somehow gathered together during that epoch to form stars and galaxies -- but how? Did stars appear first, or galaxies? And what was left behind in the void after they formed: empty space or vast drifting clouds of now-invisible gas?
How our Universe started -- and how it will end -- depends on the answers.
To explore such questions, astronomers turned an orbiting NASA telescope named "FUSE" (short for Far-Ultraviolet Spectroscopic Explorer) toward a distant quasar -- a brilliant, active nucleus of a galaxy some 10 billion light-years away, near the edge of the known Universe. For 20 days in August and October, 2000, FUSE collected the quasar's light in the far ultraviolet region of the electromagnetic spectrum. (Far ultraviolet radiation is about 5 times more energetic than the sunburn-causing ultraviolet rays familiar to beach-goers.) Other researchers using the Hubble Space Telescope and the gigantic ground-based Keck telescope in Hawaii monitored the quasar at ordinary ultraviolet and visual wavelengths.
Then the analyses -- and discoveries -- began. MORE
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