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Telescopes

Space telescopes

Carina Nebula, an image made by the HubbleCarina Nebula, an image made by the Hubble The Earth’s atmosphere stops many types of radiation from reaching the surface. To study these sorts of radiation, space telescopes stationed in Earth orbit must be used instead. These telescopes have special mirrors to reflect and focus the radiation, and electronic detectors to record the images formed, which are radioed back to Earth. Optical telescopes also benefit from being in orbit because the atmosphere distorts light rays as they pass through it. The Hubble Space Telescope is the best known of its kind. It has sent back many detailed images of stars, galaxies and nebulae that were not possible to obtain before.


Hubble Space Telescope

The HST, as viewed from Space Shuttle AtlantisThe HST, as viewed from Space Shuttle AtlantisOrbiting 559 kilometres (347 miles) above Earth is the Hubble Space Telescope (HST), launched by the Space Shuttle in 1990. It is the most complex space telescope so far. It can detect visible light, infrared and ultraviolet rays. It has special mirrors to reflect and focus images and electronic detectors to record them. Images are sent to Earth via the telescope’s antennae. It is so sensitive it could detect light from a torch 400,000 kilometres (250,000 miles) away.

After the Hubble was finally launched in 1990, scientists found a major fault in the main mirror. Although only 2.2 millionths of a metre too flat at the edges, the images it produced were out of focus. The error was corrected during a Space Shuttle mission in 1993.

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