Using the Deep Space Network's 230-foot antenna at Goldstone, California, the radar images of Asteroid 2003 SD220 were acquired when the distance to this near-Earth object (NEO) was narrowing from 12 million km to almost the flyby distance.
"The radar images data suggest that asteroid 2003 SD220 is highly elongated and at least 3,600 feet in length," said Lance Benner who leads Nasa's asteroid radar research programme.
"The data acquired during this pass of the asteroid will help us plan for radar imaging during its upcoming closer approach in 2018," he added.
Three years from now, the asteroid will safely fly past Earth again, but even closer, at a distance of 2.8 million km.
The 2018 flyby will be the closest the asteroid will get to Earth until 2070, when it is expected to safely fly past our planet at a distance of about 2.7 million km.
"There is no cause for concern over the upcoming flyby of asteroid 2003 SD220 this Christmas Eve," said Paul Chodas, manager of Nasa's Center for NEO Studies at JPL.
The closest this object will come to Santa and his eight tiny reindeer is about 28 times the distance between Earth and the moon