A 1.6-kilometre (1-mile) long asteroid on a trajectory that will carry it within 2.9 million kilometres (1.8 million miles) of Earth on 22 December, its closest approach in more than 400 years and the closest until 2070 when it will by slightly closer. The asteroid, known as 2003 SD220, was discovered in 2003 by astronomers at the Lowell Observatory in Flagstaff, Arizona.
The above radar images were obtained by NASA’s 70-metre (230-foot) dish antenna at the agency’s Goldstone Deep Space Communications Complex in California and the National Science Foundation’s 100-metre (330-foot) Green Bank Telescope in West Virginia.
The image on the left was captured 15 December when the asteroid was 4.5 million kilometres (2.8 million miles) from Earth. The middle image, obtained one day later, shows 2003 SD220 at a distance of 4 million kilometres (2.5 million miles) while the right-side image shows it one day after that at a distance of 3.6 million kilometres (2.2 million miles).
The radar images, with a maximum resolution of 3.7 metres per pixel (12 feet) show the asteroid is at least 1.6 kilometres long. The