These three radar images of near-Earth asteroid 2003 SD220 were obtained on Dec. 15-17, by coordinating observations with NASA's 230-foot (70-meter) antenna at the Goldstone Deep Space Communications Complex in California and the National Science Foundation's (NSF) 330-foot (100-meter) Green Bank Telescope in West Virginia.
The radar image on the left was obtained on Dec. 15 when asteroid 2003 SD220 was 2.8 million miles (4.5 million kilometers) from Earth. The radar image in the middle was generated from data collected on Dec. 16 when the asteroid was 2.5 million miles (4.0 million kilometers) from Earth. The image on the right was obtained on Dec. 17 when 2003 SD220 was 2.2 million miles (3.6 million kilometers) from Earth. The spatial resolution on the images is as fine as 12 feet (3.7 meters) per pixel. The radar images reveal the asteroid is at least one mile (1.6 kilometers) long.
Asteroid 2003 SD220 was discovered on Sept. 29, 2003, by astronomers at the Lowell Observatory Near-Earth-Object Search (LONEOS) in Flagstaff, Arizona -- an early Near-Earth Object (NEO) survey project supported by NASA that is no longer in operation. The asteroid will fly safely past Earth on Saturday, Dec. 22, 2018, at a distance of about 1.8 million miles (2.9 million kilometers). This will be the asteroid's closest approach in more than 400 years and the closest until 2070, when the asteroid will safely fly by slightly closer.