Synthetic aperture radar
![This radar image acquired by the SIR-C/X-SAR radar on board the Space Shuttle Endeavour shows the Teide volcano. The city of Santa Cruz de Tenerife is visible as the purple and white area on the lower right edge of the island. Lava flows at the summit crater appear in shades of green and brown, while vegetation zones appear as areas of purple, green and yellow on the volcano's flanks.](/Images/godic/202501/09/TEIDE1427.JPG")
![The surface of Venus, as imaged by the Magellan probe using SAR](/Images/godic/202501/09/Venus_globe1427.jpg")
![SAR image of Death Valley colored using polarimetry](/Images/godic/202501/09/Death-valley-sar1427.jpg")
![NASA's AirSAR instrument is attached to the side of a DC-8](/Images/godic/202501/09/AirSAR-instrument-on-aircraft1427.jpg")
Synthetic aperture radar (SAR) is a form of radar which is used to create images of objects, such as landscapes – these images can be either two or three dimensional representations of the object. SAR uses the motion of the radar antenna over a targeted region to provide finer spatial resolution than is possible with conventional beam-scanning radars. SAR is typically mounted on a moving platform such as an aircraft or spacecraft, and has its origins in an advanced form of side-looking airborne radar (SLAR). The distance the SAR device travels over a target in the time taken for the radar pulses to return to the antenna creates the large "synthetic" antenna aperture (the "size" of the antenna). As a rule of thumb, the larger the aperture is, the higher the image resolution will be, regardless of whether the aperture is physical (a large antenna) or 'synthetic' (a moving antenna) – this allows SAR to create high resolution images with comparatively small physical antennas.