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APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
The Lyman Alpha Forest
Explanation: We live in a forest. Strewn throughout the universe are “trees” of hydrogen gas that absorb light from distant objects. These gas clouds leave numerous absorption lines in a distant quasar 's spectra , together called the Lyman-alpha forest . Distant quasars appear to be absorbed by many more Lyman-alpha clouds than nearby quasars, indicating a Lyman-alpha thicket early in our universe. The above image depicts one possible computer realization of how Lyman-alpha clouds were distributed at a redshift of 3. Each side of the box measures 30 million light-years across. Much remains unknown about the Lyman-alpha forest , including the real geometry and extent of the clouds , and why there are so many fewer clouds today .
| Date | January 26, 2003 |
|---|---|
| Credit | Credit & Copyright: J. Shalf, Y. Zhang ( UIUC ) et al., GCCC |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |