A new study using data from NASA's Spitzer Space Telescope
suggests a cause for the mysterious glow of infrared light seen
across the entire sky. It comes from isolated stars beyond the
edges of galaxies. These stars are thought to have once belonged
to the galaxies before violent galaxy mergers stripped them away
into the relatively empty space outside of their former homes.
The findings disagree with another theory explaining the same
background infrared light observed by Spitzer. A group led by
Alexander "Sasha" Kashlinsky of NASA's Goddard Space Flight
Center in Greenbelt, Md., proposed in June this light, which
appears in Spitzer images as a blotchy pattern, is coming from
the very first stars and galaxies. In the new study, Cooray and
colleagues looked at data from a larger portion of the sky,
called the Bootes field, covering an arc equivalent to 50 full
Earth moons. These observations were not as sensitive as those
from the Kashlinsky group's studies, but the larger scale
allowed researchers to analyz