Telescopes from the Ground Up

A chilly telescope takes the heat

The Spitzer Space Telescope took its place in the cosmos in 2003. It will spend 2 ½ to 5 years studying infrared light. Although telescopes on mountaintops can study certain infrared wavelengths, most infrared radiation is absorbed by the Earth’s atmosphere.

Spitzer gets a much clearer view of the wavelengths of infrared light that can be studied from the Earth, and makes it possible to examine the infrared wavelengths that are blocked by the Earth’s atmosphere.

So cool …

Spitzer is named after the astrophysicist Lyman Spitzer Jr., who was the first to propose putting a telescope in space. The highly unique telescope is the last of four telescopes in NASA’s Great Observatories program. Since it studies infrared light, which we perceive as heat, it must be kept extraordinarily cold to keep its own heat from interfering with the detection of infrared radiation from space. In addition to being extremely well insulated and shielded from heat, Spitzer has a liquid helium tank that helps keep the parts of the science instruments that need to stay chilly as cold as 1.4 Kelvin. That’s very close to 0 Kelvin, or “absolute zero,” the lowest temperature possible, at which all motion stops.

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Space Telescopes
Diagram of the orbit of the Spitzer Space Telescope, in orbit with Earth around the Sun.
Illustration of the Spitzer Space Telescope in orbit with Earth around the Sun.Enlarge picture
The Spitzer Space Telescope
Year launched: 2003
Telescope type: Reflector
Light collector: Beryllium metal mirror
Mirror diameter: 33.5 inches
(85 cm)
Light observed: Infrared
Discovery Highlights:
  • Has seen through dust clouds in our galaxy to better allow the study of star formation and black holes.