Infra-red radiation is a part of the electromagnetic spectrum, and is one
of the ways in which thermal energy (or heat) are transferred from hot to
cold objects. Any object will emit some IR radiation, depending how hot
it is and what type of material it is made from. This fact is sometimes
expolited in seeing things which otherwise might be difficult to see.
For example the image to the right shows how a person walking in front
of a truck
can be seen using far IR light, which is invisible to our eyes. The hotter
the object, the brighter the image.
Thermal infra-red imaging is used primarily by NASA for earth bound satellite
observation and by meteorological satellites, which can see through various
weather conditions, and detect differences in temperature between clouds,
sea and land.
image shows two photos side by side. The left image is a normal photo of
the Yellowstone N.P. fire. On the right is a thermal satellite image, which
can see through the smoke.
For a more detailed description of how thermal IR
imaging is done, click here:
More information generally can be found at
Observatorium Education Resources homepage.