These three radar images of the 2003 hippopotamus-shaped asteroid SD220 were captured between December 15 and 17, 2018 using NASA's Goldstone antenna, the Arecibo Observatory in Puerto Rico and the Green Bank Telescope in West Virginia.
Credit: NASA / JPL-Caltech / GSSR / NSF / GBO
If only a hippo does this Christmas, Santa will have space rock for you.
A small asteroid will fly safely across Earth on Saturday (Dec. 22) and, according to NASA people, looks like the mighty hippopotamus on new radar images. The asteroid, called the 2003 SD220, is also approaching Earth in more than 400 years and will not be closer until 2070, according to NASA officials. He flew across the Earth for the last time on Christmas Eve 2015.
"Do you want a hippopotamus for Christmas?" NASA Jet Propulsion Laboratory employees wrote on Twitter Friday (December 21) "You're in luck.The #asteroid 2003 SD220 hippopotamus will fly safely across the Earth on Saturday, December 22, at a distance of about 2.9 million kilometers." (If you're wondering about the Christmas-hippo connection, watch this lovely video clip of "I Want a Hippo for Christmas," sung by 10-year-old Gayla Peevey in 1953.)
The new radar images have revealed that the 2003 asteroid SD220 is almost 1.6 km long and has a shape "similar to that of the exposed portion of a hippopotamus crossing a river," JPL officials said in a statement. The size of the asteroid and the fast flights of the Earth make the asteroid potentially dangerous for NASA, but does not pose a threat to our planet, officials said. [Potentially Dangerous Asteroids in Pictures]
The radar images were taken between Dec. 15 and Dec. 17 by scientists with NASA's JPL, Goldstone's antenna in California, Arecibo Observatory in Puerto Rico and the Green Bank Telescope of the National Science Foundation in West Virginia. The Goldstone and Arecibo instruments removed signals from asteroid microwaves that were picked up by the Green Bank Telescope to create detailed radar images of the size and shape of the rock.
"Radar images reach an unprecedented level of detail and are comparable to those obtained from a spacecraft overfly," said Lance Benner of JPL in Pasadena, Calif., The lead scientist for Goldstone's observations in the JPL statement. "The most visible surface feature is a prominent ridge that seems to partially envelop the asteroid near one end."
The summit rises 100 meters above its surroundings, and the asteroid is filled with bright spots that may be reflections of boulders, Benner said. "The images also show a cluster of dark, circular features near the right edge, which may be craters," he added.
The new observations are about 20 times more detailed than those made in 2015, when the 2003 asteroid SD220 flew across the Earth for the last time. At the time, it was much further than its current visit, NASA officials said.
The new images also confirm important details about the 2003 asteroid SD220, added NASA. They show that the asteroid rotates only once every 12 days – a strangely slow spin for a space rock. Also has an unsteady movement that NASA officials compared to poorly played football (or maybe a meandering hippopotamus?).
"Known as" non-main axis spin, "it's unusual among near-Earth asteroids, most of which spin on their shortest axis," NASA officials said of the asteroid movement.
Refining the rotation, size and shape of the 2003 SD220 asteroid, the new radar images will help scientists understand how it has formed and evolved over time, the researchers said. The observations were funded by NASA's Own Object Observation Program, which routinely tracks potentially dangerous asteroids for the Office of Planetary Defense Coordination that oversees the agency's Planetary Defense Program.