Related topics: nasa

Future of Earth's defense is ground-based planetary radar

Powerful radar systems have played a major role in the study of planets, moons, asteroids, and other objects in our Solar System for several decades, and now have a "unique role" to play in planetary defense—"providing ...

There are deposits of ice at Mercury's poles, too

Although the Arecibo radio telescope is no more, it continues to deliver scientific discoveries. There is a wealth of Arecibo data astronomers continue to mine for new discoveries, and one of them is thanks to an astronomical ...

The science behind winter storm chasing experiments

As the snowstorm headed through New York on February 24, one professor at Stony Brook University in Stony Brook, New York spent the hours leading up to it preparing his students to head right into the storm.

Hope for present-day Martian groundwater dries up

Liquid water previously detected under Mars' ice-covered south pole is probably just a dusty mirage, according to a new study of the red planet led by researchers at The University of Texas at Austin.

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Radar

Radar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for radio detection and ranging. The term has since entered the English language as a standard word, radar, losing the capitalization. Radar was originally called RDF (Radio Direction Finder, now used as a totally different device) in the United Kingdom.

A radar system has a transmitter that emits microwaves or radio waves. These waves are in phase when emitted, and when they come into contact with an object are scattered in all directions. The signal is thus partly reflected back and it has a slight change of wavelength (and thus frequency) if the target is moving. The receiver is usually, but not always, in the same location as the transmitter. Although the signal returned is usually very weak, the signal can be amplified through use of electronic techniques in the receiver and in the antenna configuration. This enables radar to detect objects at ranges where other emissions, such as sound or visible light, would be too weak to detect. Radar is used in meteorological detection of precipitation, measuring ocean surface waves, air traffic control, police detection of speeding traffic, and by the military.

This text uses material from Wikipedia, licensed under CC BY-SA