Close Encounters Of The 2016 RB1 Kind — Asteroid Dips Into Earth’s Space Tomorrow

Artist's view of a close-approaching asteroid such as 2016 RB1. Credit: NASA
Artist’s view of a close-approaching asteroid such as 2016 RB1. Credit: NASA

A big rock’s going to fly over our heads tomorrow. At around 12:11 p.m. Central Daylight Time (17:11 UT) Sept. 7, asteroid 2016 RB1 will zip just 21,000 miles from the surface of the Earth. The object was only discovered just two days ago (Sept. 5) by the Catalina Sky Survey. Based on its distance and brightness, RB1 is somewhere between 24 and 52 feet across (7.3-16 meters) or about as long as two Mack trucks placed end to end.

Many asteroids pass near Earth each month, but this one’s a bit unusual because it will pass within the geosynchronous satellite belt, which lies 22,236 miles (35,786 km) out. Satellites here orbit at the same rate as the Earth rotates, so they hover over one location of the planet day and night. Weather satellites as well as many communications satellites are parked there. Yet chance of the asteroid striking any one of the approximately 400 satellites is vanishingly rare, since there’s a lot of space out there, and RB1 will make only the briefest of passes at a considerable angle to the belt.

Nine radar images of near-Earth asteroid 2007 PA8 obtained between by NASA's 230-foot-wide (70-meter) Deep Space Network antenna. Credit: NASA/JPL-Caltech
When asteroids pass close enough, we can ping them with radar and determine their shapes, rotation rate and even see surface details as in this sequence of near-Earth asteroid 2007 PA8 obtained by NASA’s 230-foot-wide (70-meter) Deep Space Network antenna. Credit: NASA/JPL-Caltech

Whenever an Earth-approaching asteroid like this one zips this close, amateur astronomers like to try tracking it in their telescopes. When nearest, 2016 RB1 will be moving rapidly south in the morning sky to the tune of 34° per hour or a tad more than the moon’s apparent diameter every minute. Flying past at over 18,000 mph (29,000 km/hr), the asteroid will move in real time even when viewed at low magnification, appearing much like a slow satellite.

Animation of asteroid 2016 RB1 using photographs taken this evening Sept. 6 from Italy. Credit: Gianluca  Masi
Animation of asteroid 2016 RB1 using photographs taken this evening Sept. 6 from Italy. Credit: Gianluca Masi

Wish I could see it. Observers in Hawaii and Japan will get a look at it on the way in before dawn tomorrow morning, when RB1 will shine around magnitude 12.6. All you need is a darn good map a 6-inch or larger telescope. Australia, New Zealand and South Africa are even better placed; they’ll catch the flying space truck at its predicted brightest magnitude of 12.2. Unfortunately, skywatchers in the northern hemisphere won’t have it so good. Too faint to be seen from Europe, dedicated observers in the Americas with 10-inch and larger telescopes will see or photograph it as a faint 14th magnitude object in Pisces tomorrow morning several hours before closest approach.

Not only will the asteroid dare to violate our geosynchronous space, it will also pass rather close to the moon, just 178,000 miles (287,000 km) away. No harm will come of either encounter as the asteroid will be moving rapidly along its orbit and continue back from whence it came. With a slight alteration. It passes so close to Earth that our planet’s gravity will almost certainly change up its orbit after the flyby.

Resources:

* Bill Gray’s site devoted to 2016 RB1 (has positions and information for plotting a map)

* NASA’s Near Earth Object Program