
The four Great Observatories are a series of space telescopes meant to give the most complete picture of objects across many different wavelengths. Each observatory studies a particular wavelength region in great detail.
The telescopes, in order of launch, are: the Hubble Space Telescope (1990), Compton Gamma Ray Observatory (1991), Chandra X-ray Observatory (1999), and Spitzer Space Telescope (2003). The chart at top right shows each telescope above the wavelength region it was built to observe. All except for CGRO are currently in orbit.
Sometimes several of the Great Observatories are used to look at the same object. Astronomers can analyze an object thoroughly by studying it in many different kinds of light. An object will look different in X-ray, visible, and infrared light.
The images at right show the remains of an exploded star (Kepler's supernova), as seen by three of the Great Observatories.