Related topics: nasa

Understanding a satellite's death spiral

Down on the ground, death equals stillness—but not in space. Abandoned satellites are prone to tumble in unpredictable ways, and an ESA project with the Astronomical Institute of the University of Bern sought to better ...

Using AI to track icebergs

Researchers are using a new AI tool to detect icebergs in the Southern Ocean. This is the first step in being able to track the complete life cycle of most icebergs across Antarctica from satellite data. The study, "Unsupervised ...

Radar tracks unfortunate creatures trapped in tropical cyclones

In the aftermath of Super Typhoon Lekima, which struck mainland China in early August 2019, a number of bird species were recorded in places they had never been seen before. A new study reveals the likely reason behind how ...

Sentinel-1 reveals shifts from Morocco earthquake

Following the devastating earthquake that struck Morocco on 8 September, satellite data have been made available through the International Charter "Space and Major Disasters" to help emergency response teams on the ground.

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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