History
The sky glows at gamma ray wavelengths as well as visible ones. If our eyes could see gamma rays
(and the atmosphere didn't absorb them), the sky would look like the adjacent image,
which shows the intensity of high energy gamma rays plotted in galactic coordinates as measured
by the Compton Gamma Ray Observatory
(Ref).
The diffuse glow running horizontally through the image is from gamma ray sources
in the plane of our galaxy. The bright spots to the right of center in the galactic plane are pulsars.
Brighter spots above and below the plane of the galaxy are gamma rays coming from distant quasars. Many of
the fainter sources are of unknown origin at this point.
In addition to the constant flux of gamma rays illustrated in the adjacent image, there are also
observed sudden pulses of gamma rays lasting typically seconds in which enormous amounts of energy appear
to be poured out in gamma rays by still unknown sources.
These
Gamma Ray Bursts
pose one of the greatest mysteries of modern
astronomy. First discovered by military satellites looking for the telltale
signature of clandestine nuclear explosions, they are now studied extensively for
their scientific merit. Here is a
history of their discovery.