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Fermi Measures Light from All the Stars That Have Ever Existed
This plot shows the locations of 150 blazars (green dots) used in the a new by the Fermi Gamma-Ray Telescope. Credit: NASA/DOE/Fermi LAT Collaboration
All the light that has been produced by every star that has ever existed is still out there, but “seeing” it and measuring it precisely is extremely difficult. Now, astronomers using data from NASA’s Fermi Gamma-ray Space Telescope were able to look at distant blazars to help measure the background light from all the stars that have ever existed. This enabled them to make the most accurate measurement of starlight throughout the universe, which in turn helps establish limits on the total number of stars that have ever shone.
“The optical and ultraviolet light from stars continues to travel throughout the universe even after the stars cease to shine, and this creates a fossil radiation field we can explore using gamma rays from distant sources,” said lead scientist Marco Ajello from the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University in California and the Space Sciences Laboratory at the University of California at Berkeley.
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Read the rest of Fermi Measures Light from All the Stars That Have Ever Existed (738 words)
© nancy for Universe Today, 2012. | Permalink | 2 comments |
Post tags: extragalactic background light, Fermi Space Telescope
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2012-11-01 14:03:09
Source: http://www.universetoday.com/98296/fermi-measures-light-from-all-the-stars-that-have-ever-existed/
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