SIRTF (Space Infrared Telescope Facility)

This satellite can observe wavelengths that cannot be seen from earth. This instrument can image dust clouds and planets around nearby stars. The new Hubble infrared spectrometer will replace many of the tasks that this satellite has performed.

Infrared radiation has lower energy than visible light and is produced by relatively cool objects, in the temperature range between 3 degrees and 1500 degrees Kelvin. (Ambient temperature on earth is about 300K.) Quite often, visible light from cosmic sources is obscured by interstellar dust, but infrared light passes through. Thus, invisible stars and galaxies can be "seen" in the infrared region. The redshift due to the expansion of the Universe shifts energy to longer wavelengths. The amount of the shift is directly proportional to how far away an object is. As a result, the high z objects we observe today are as they appeared when they (and the Universe) was younger (because the speed of light is finite). Since the Universe is expanding most of the visible and UV radiation from astronomical objects has shifted into the IR.


SIRTF (Space Infrared Telescope Facility) Home Page

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