a device that sends out radio waves and picks them up again after the waves strike another object and bounce back
Sentences:
Radar is used to help predict weather and measure waves of the ocean.
Police officers can tell how fast a car is going by using a
radar device.
More Information:
http://spaceplace.nasa.gov/en/kids/srtm_makemap3.shtml →
http://southport.jpl.nasa.gov/desc/imagingradarv3.html →
http://southport.jpl.nasa.gov/html/sat_animation.html →
http://science.nasa.gov/headlines/y2008/29feb_radarmoon.htm →