Infrared Telescopes Discover Beautiful Worlds


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The invisible radiation infrared spectrum was discovered by Sir William Herschel in 1800 when a thermometer registered heat when placed below the Sun's red end spectrum. In 1969, the first ground based infrared sky survey discovered 5,612 cool stars, and in 1983, when IRAS was launched, 250,000 cosmic infrared sources were discovered.

Three thousand kilometers plumes of gas were viewed by infrared telescopes when the Shoemaker-Levy 9 impacted with the planet Jupiter in 1994; and, the Infrared Space Observatory found widespread water in space from interstellar clouds to moons in 1998.

The major infrared telescopes: UK Infrared Telescope with a 3.8 m mirror diameter located in Hawaii; NASA Infrared Telescope Facility with a 3.0 m mirror diameter located in Hawaii; Caltech Submillimeter with a 10 m mirror diameter located in Hawaii; James Clerk Maxwell with a 15 m mirror diameter located in Hawaii; Kuiper Airborne Observatory with a 0.9 m mirror diameter located on Lockheed C141; SOFIA with a 2.5 m mirror diameter located on Boeing 747SP; IRAS with a 0.6 m mirror diameter located at Polar orbit; ISO with a 0.6 m mirror diameter located in Elliptical orbit; and, Space Infrared Telescope Facility with a 0.85 m mirror diameter located in Solar orbit.

Infrared is heat radiation. Infrared is capable of traveling through interstellar dust in a straight line, but only cooler stars, which are around 3,000 degrees Centigrade gives off infrared. With infrared telescopes, scientists have information that optical telescopes are incapable of giving.

Infrared wavelengths are just beyond the red end visible spectrum, and covers a larger part of the electromagnetic spectrum, or from 700 nanometers, which is a millionth of a millimeter to one millimeter, and the beginning of radio waves.

Infrared detectors pick up heat variations of an object, from cool stars at 3,000 degrees Centigrade to the cold dust clouds of -250 degrees Centigrade. Our universe had gas clouds reaching a heat of a million degrees Centigrade, which is the reason the stars with a temperature of 3,000 degrees is referred to as cool.

The European Infrared Space Observatory gave new information on colliding galaxies, nurseries for newborn stars, and interstellar clouds. The ISO had been enclosed in a flask with a temperature of -270 degrees Centigrade to minimize the interference its own heat would present. The ISO had to quit its observations after three years, since the liquid helium cooling it was exhausted.

Optical and infrared telescopes have similar features, but an infrared needs a cooling system. The cooling system offsets any heat the telescope has to provide clearer pictures of infrared red waves from space. They are also sensitive to cool and lukewarm materials, such as, dust and gas clouds with a width of hundreds of light-years across. Heat from the newborn stars will warm the dust and gas clouds to 1,000 degrees Centigrade, or white areas, but optical telescopes cannot pick up the hot wavelengths.


1. Couper, Heather and Nigel Henbest. Space Encyclopedia DK Publishing, Inc.: NY 1999

2. Editors. Secrets of the Universe. International Master Publishing: US. 1999