The Spitzer Space Telescope was a space observatory launched by NASA in 2003. It was designed to observe the universe in infrared light, allowing scientists to study celestial objects that are too cool or faint to be seen in visible light. Spitzer helped to explore various astronomical phenomena, including the formation of stars, the composition of distant galaxies, and the presence of exoplanets. Spitzer operated for over 16 years, providing valuable data that enhanced our understanding of the cosmos. It was part of NASA's Great Observatories program, which also included the Hubble Space Telescope, Chandra X-ray Observatory, and Compton Gamma Ray Observatory. The mission concluded in January 2020, but its discoveries continue to influence astronomy.