Originally called "FIRST," for "Far InfraRed and
Submillimetre Telescope," the spacecraft was renamed for
Britain's Sir William Herschel, who discovered in 1800 that
the spectrum extends beyond visible light into the region
that we today call "infrared."
The Herschel Space Observatory is a space-based telescope
that will study the Universe by the light of the
far-infrared and submillimeter portions of the spectrum.