thermal or blackbody radiation:
Emitted by all matter in the universe,
this radiation’s spectrum depends
only on the temperature of the object
emitting it. Light from the Sun and
other stars, for instance, approximates
blackbody radiation. Because higher
temperatures produce shorter
wavelengths, a star’s color indicates
its temperature: yellow stars are
relatively cool (5,700 degrees Kelvin),
while blue-white ones are hotter
(10,000+ degrees Kelvin). Blackbody
radiation receives its name from the
concept that even a perfectly black
object reflecting no light would give