In the early 1800s, the British astronomer Sir
William Herschel discovered that sunlight consisted not only of
visible light that we can see with our eyes, but also infrared energy
beyond the visible spectrum. This led to the development in the
1900s of special telescopes to survey the skies at infrared wavelengths.
The Infrared Astronomical Satellite places
such a telescope in orbit above the interference of Earth's atmosphere.
Operating for 10 months, two its most significant findings are the
discoveries of solid material around the stars Vega and Fomalhaut,
located some 26 and 22 light-years from Earth, respectively. This
strongly suggests the existence of planetary systems around other
stars (later confirmed by future telescope observations).