The asteroid is considered a near-Earth object, but it'll zoom past us at a safe distance of 1.8 million miles (2.9 million kilometers) on Saturday. This is 2003 SD220's closest approach to our planet in 400 years, though it will slide by slightly closer in 2070.
The asteroid is about 1 mile (1.6 kilometers) long.
thinks it looks like a "hippopotamus wading in a river."
The radar images came from mid-December through coordinating the efforts of the Goldstone Deep Space Communications Complex in California, the National Science Foundation's Green Bank Telescope in West Virginia and the Arecibo Observatory in Puerto Rico.
"The radar images achieve an unprecedented level of detail and are comparable to those obtained from a spacecraft flyby," said NASA scientist Lance Benner. Benner says NASA noticed a distinctive ridge along one end and numerous small bright spots that may be reflections from boulders.
Asteroid 2003 SD220 is also notable for its slow, complicated rotation, which NASA compares to that of a poorly thrown American football. The data NASA gathered will help scientists better understand how similar space bodies formed and evolved.
While 2003 SD220 is classified as a "potentially hazardous asteroid" thanks to its size and travel path, NASA confirmed "it does not pose a future impact threat to Earth."