Earth-based astronomy

Introduction.
There are many powerful telescopes on Earth that provide a good view of space.
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• large optical telescopes produce images that can be Analyzed by computer. They are put in building on high ground so they can avoid the lights and polluted air of towns and cities.
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• Radio telescopes pick up radio waves from space that are usually produced by clouds of gas or dust. Radio waves are one of the few kinds of space radiation that can pass through Earth's atmosphere.
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Kitt peak observatory,
•There are several telescopes on kitt peak in Arizona,USA, including a reflector 4 meters across. It also has the world's largest solar telescope (for observing the sun).
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• The MMT (Multiple Mirror Telescope) on mount Hopkins, Arizona, USA, has six mirrors all 1.8 meters wide.
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Arecibo,
• The largest single radio telescope dish in the world is at Arecibo in Puerto Rico. It is 305 metres across.