Arecibo Obervatory
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Photo by David Parker/Science Photo Library, London
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Radar is short for radio detection and ranging. A transmitter emits
pulses of high frequency electromagnetic waves (radio waves). These
waves strike conductive objects and are backscattered to the receiver. A
radar echo shows up on a monitor. This way radar
operators know where the object is. A computer measures the time it
takes for the signal to reflect off the target and then calculates how
far away it is.
Radar is used extensively in the military. It was both an offensive and
defensive weapon. Agressors can use radar to locate areas where they
want to attack. Defenders can use radar as an early warning of an
impending attack. New stealth technology has begun to make current radar
systems useless because of the way objects are designed to not reflect
radar waves. One drawback to using radar in a battle situation is
that detection is a two way street. If you use radar to try and find an
enemy, that enemy will know where you are. This is just like using a
flashlight in the dark.
There are many scientific uses of radar, but the most well-known by the
public is weather
radar. Weather radar is an important forecasting tool, especially
for now-casts (very short-term forecasts). Radar is also used to study
other aspects of the atmosphere, such as mapping wing patterns. If
environmentalists know how the wind blows in the upper atmosphere, they
can predict what areas could be affected by pollution dispursion.
Planetary probes such as Magellan also use radar for
surface mapping missions.
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