Telescope

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A small, old spyglass

A telescope is an important tool for astronomy that gathers and focuses light. Some do this with curved mirrors, some with curved lenses, and some with both. Telescopes make far-away things look bigger, brighter and closer. Galileo was the first person to use a telescope for astronomy, but he did not invent them. The first telescope was invented in the Netherlands in 1608. Some telescopes, not mainly used for astronomy, are binoculars, camera lenses, or spyglasses.

A large, modern telescope

The word "telescope" is usually used for light your eyes can see, but there are telescopes for "invisible" light. Infrared telescopes look like normal telescopes, but have to be kept cold since all warm things give off infrared light. Radio telescopes are like radio antennas, usually shaped like large dishes.

X-ray and Gamma ray telescopes have a problem because the rays go through most metals and glasses. To solve this problem, the mirrors are shaped like a bunch of rings inside each other so the rays strike them at a shallow angle and are reflected. These telescopes have to be placed in satellites because not enough of this radiation reaches the Earth. Other telescopes are also put in orbit so the Earth's atmosphere doesn't interfere.

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