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Karl Jansky first discovered radio waves in 1931. In the late 1930’s an American engineer named Grote Reber built the first-bowl shaped radio telescope and operated it in his backyard. His radio telescope collected and measured faint radio waves given off by objects in space. The Sun and the center of our galaxy were found to be strong sources of radio waves. Radio Telescopes also detected strong radio waves coming from black or dark places in space. These were discovered to be exploded stars and a rare type of distant galaxy. Radio telescopes can produce images of objects in space that would have been missed by an optical telescope since optical telescopes need to have some kind of light to see an object and a radio telescope doesn’t. The discoveries made possible by radio telescopes include giant clouds of gas; pulsars, which are collapsed stars that send out regular pulses of radio waves; and quasars, which are extremely distant star-like objects that produce an enormous amount of radiation.
How It Works
Many radio telescopes use a bowl-shaped reflector called a dish to collect sound waves from space. The reflector focuses the waves onto an antenna that changes them into electric signals. A radio receiver amplifies these signals and records their strength at different frequencies and from different directions. The information is analyzed by a computer that uses the signals to draw a picture of the source of the radio waves or to analyze the chemicals of the source. Large radio telescopes are also used as giant radar systems to map the surfaces of the moon and planets. Scientists can send radio waves out into space. Radio waves bounce off of moons, planets, or other objects in space and receivers record the radio echoes that bounce back to Earth. Astronomers call this technique, "radar mapping." Radar mapping is kind of like an ultrasound with a baby. The machine will bounce sound waves off the baby inside the mother, and when it bounces back, it will form a picture. The sound is a vibration and when the machine picks up the vibration bouncing back, it is catching the echo. It is also like a fish detector. The fish detector sends out a sound wave. The fish detector collects the sound wave when it comes back. The computers in the fish detector will know how far the fish are, depending on how long it took the sound wave to travel back to the boat. |
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Space Exploration of the Past, Present, and Future
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