“Our human window on the Universe is terribly small within a stunningly small range of wavelengths. With our eyes we see wavelengths between 0.00004
and 0.00008 of a centimeter (where, not so oddly, the Sun and stars
emit most of their energy). The human visual spectrum from violet to
red is but one octave on an imaginary electromagnetic piano with a
keyboard hundreds of kilometers long.”
James
Kaler, astronomer and author of “Heavens Gate: From Killer Stars to the
Seeds of Life, How We are Connected to the Universe.”
The
image below is an infrared photo of M82 is a remarkable galaxy of
peculiar type in constellation Ursa Major. It is usually classified as
irregular, though probably a distorted disk galaxy, and famous for its
heavy star-forming activity, thus a prototype member of the class of
starbursting galaxies. In the infrared light, M82 is the brightest
galaxy in the sky; it exhibits a so-called infrared excess, being much
brighter at infrared wavelengths than in the visible part of the
spectrum. Over 100 young globular clusters have been discovered in M82
with the Hubble Space Telescope. Their formation is probably another
effect triggered by a tidal encounter with M81 between 50 and several
100 million years ago.
Much of what you see above is outside our human visual band, our eyes
cannot register wave photons no matter how powerful they may be. Longer
that the visual wavelength limit -up to about a millimeter-lies the
infrared. At the short end is violet, with orange, yellow, green, blue
and hundreds of overlapping shades. Longer waves, into
kilometer-wavelengths toward the unknown end are what we call “radio.”
than the visual limit are the ultrviolet -all running in the vacuum at
the speed of light. At less than a percent of the wavelength of visual
light are X rays, and at a factor of 100 smaller are the deadly gamma
rays.
is the entersion of “human sight” -opening the electromagnetic spectrum
to our view and discovery beginning in the 1930s with radio estronomy
and ending with NASA’s great fleet of space observatories and the Fermi
Gamma-ray Space Telescope (FGST, formerly GLAST), working to unveil the
mysteries of the high-energy universe. Launched into orbit on June 11,
FGST studies the most energetic particles of light, observing physical
processes far beyond the capabilities of earthbound laboratories..
composite of our Milky Way’s core is compsed of images from the Hubble
Space Telescope in near-infrared light, the Spitzer Space Telescope in
infrared light, and the Chandra X-ray Observatory in X-ray light. A
mosaic of vast star fields is visible, along with dense star clusters,
long filaments of gas and dust, expanding supernova remnants, and the
energetic surroundings of what likely is our Galaxy’s central black
hole.
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