The Spitzer Space Telescope is a telescope launched into space by NASA in 2003. It is the fourth telescope in the Great Observatories program (the Hubble Space Telescope was the first). The Hubble Space Telescope takes pictures of visible light, and the Spitzer Space Telescope takes pictures of infrared light. Unlike Hubble, Spitzer orbits the Sun instead of the Earth.

The Spitzer Space Telescope is named after the scientist Lyman Spitzer. It was planned to last for 2.5 years, but it actually lasted until 2009 when it exhausted its supply of coolant. Some parts of the telescope can work even when they are warm, and are still working.

The Spitzer Space Telescope was able to see very good detail. Spitzer was the first telescope that could see light from extrasolar planets (planets outside the Solar System.^[1]) It was also able to see some of the first stars in the universe, believed to be only 100 million years after the Big Bang.^[2]

• Spitzer Space Telescope website at NASA.
• Spitzer Space Telescope website at Caltech.