Launch of Spitzer Space Telescope

The Spitzer Space Telescope was an infrared space observatory launched by NASA on a Delta II rocket, and the last of the agency's four Great Observatories. It followed Earth in its orbit around the Sun, which kept it away from the heat of the Earth and allowed it to operate at very low temperatures. Infrared light can pass through dust clouds, so Spitzer could observe star-forming regions, dusty galaxies and the atmospheres of exoplanets. It helped reveal the seven Earth-sized planets of the TRAPPIST-1 system. Its liquid coolant ran out in 2009, after which it continued in a warm mission with two of its detectors. It was switched off in January 2020 after more than sixteen years of operation.

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