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- Infrared radiation often
comes from dust that
absorbs visible and
ultraviolet starlight and
then reradiates it at
longer wavelengths.
That’s why Spitzer proved
so adept at tracing the
dust-laden spiral arms of
nearby galaxies. In this
image, the telescope
revealed the winding
arms of M81 in Ursa Major
from 12 million light-years
away. NASA/JPL-CALTECH/S. WILLNER
(HARVARD-SMITHSONIAN CfA)
2. The tangled spiral
arms of M101 glow with
a pinkish hue in this
Spitzer portrait. Located
22 million light-years
away in Ursa Major,
M101 shows patchy
spiral arms that are
not as well defined as
in typical grand design
spirals. NASA/JPL-CALTECH
3. Although Spitzer
revealed the Milky Way to
be a barred spiral galaxy,
our home’s structure was
harder to discern than
that of more distant
examples such as NGC
1097 in Fornax. Spitzer
scientists color-coded
this image so the galaxy’s
dusty bar and spiral arms
appear pink. The space
observatory also revealed
a ring of stars around the
supermassive black hole
that lurks at the galaxy’s
center. NASA/JPL-CALTECH/THE
SINGS TEAM (SSC/CALTECH)
4. Spitzer’s infrared
vision captured different
components of the Large
Magellanic Cloud, the
Milky Way’s largest
satellite galaxy. Blue
depicts light from older
stars, red reveals dust
heated by stars, and
green shows cooler
interstellar gas and dust
grains. Spitzer’s sharp eye
captured nearly a million
objects that hadn’t been
seen before.
NASA/JPL-CALTECH/M. MEIXNER (STScI)
AND THE SAGE LEGACY TEAM