A small asteroid designated 2016 RB1 safely flew past Earth this week at a distance of about 25,000 miles (40,000 kilometers, or just less than 1/10th the distance of Earth to the moon).

Because the asteroid's orbit carried it below (or over) Earth's south pole, it did not pass within the orbits of communication or weather satellites.

2016 RB1 is estimated to be between 25 to 50 feet (7 and 16 meters) in diameter. It is the closest the space rock will come to Earth for at least the next half century.

Asteroid 2016 RB1 was discovered on Sept. 5, 2016, by astronomers using the 60-inch Cassegrain reflector telescope of the Catalina Sky Survey, located at the summit of Mount Lemmon in the Catalina Mountains north of Tucson, Arizona - a project of NASA'S NEO Observations Program in collaboration with the University of Arizona.

The Center for NEO Studies website has a complete list of recent and upcoming close approaches, as well as all other data on the orbits of known NEOs (near-Earth objects), so scientists and members of the media and public can track information on known objects.