These images of an asteroid that is at least 3,600 feet (1,100 meters) long were taken on Dec. 17, 2015, (left) and Dec. 22 (right) by scientists using NASA's 230-foot (70-meter) Deep Space Network antenna at Goldstone, California. This asteroid, named 2003 SD2020, will safely fly past Earth on Thursday, Dec. 24, at a distance of 6.8 million miles (11 million kilometers). On Dec. 17, it was about 7.3 million miles (12 million kilometers) from Earth. By Dec. 22, it was closing in on its Christmas Eve flyby distance. Credits: NASA/JPL-Caltech . . .