Telescopes from the Ground Up

A telescope penetrates space with X-ray vision

In 1970, the United States sent its first X-ray telescope into space. In honor of its Kenyan launch site, the telescope was named Uhuru, Swahili for "freedom." Uhuru spent three years scanning the sky for X-ray sources that could never have been detected from the ground.

Twenty-nine years later, NASA launched the most sophisticated X-ray observatory it had ever built: the Chandra X-ray Observatory, named after the Nobel prize-winning physicist Subrahmanyan Chandrasekhar.

Eye in the sky

Chandra is positioned 200 times higher than the Hubble Space Telescope, in an elliptical, or oval-shaped, orbit. It has been able to detect X-ray sources 20 times fainter than anything previously picked up by an x-ray telescope and can be used to study objects that emit X-rays, such as black holes, supernovae and dark matter.

X-rays, unlike visible light rays, are rarely observed and difficult to catch. Chandra, the third telescope in NASA’s Great Observatories program, captures its X-rays with barrel-shaped mirrors unlike anything on a telescope that studies visible light.

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Space Telescopes
Diagram of the highly elliptical orbit of the Chandra X-ray observatory around Earth.
Artist illustration of the Chandra X-Ray observatory in orbit.Enlarge picture
The Chandra X-ray Observatory
Year launched: 1999
Telescope type: Reflector
Light collector: 8 iridium-coated glass mirrors
Mirror diameter: Each 32.8 inches
(83.3 cm)
Light observed: X-ray
Discovery Highlights:
  • Has allowed astronomers to study energetic events such as black holes, supernovae, and colliding galaxies. Has found new stars that may have planet-forming disks around them.