Two asteroids, several meters in diameter and in unrelated orbits, will pass within the moon’s distance of Earth on Wednesday, Sept. 8.
There are an estimated 50 million unknown asteroids. A 33-foot-wide near-Earth object could pass harmlessly between Earth and the orbit of the moon every day. Such an asteroid might hit Earth’s atmosphere once every 10 years, but because of its small size, it would pose no substantial threat to the people or property below. They break up in the atmosphere and only meteorites might hit the ground.
Both asteroids should be observable near closest approach to Earth with moderate-sized amateur telescopes. Neither of these objects has a chance of hitting Earth. A 10-meter-sized near-Earth asteroid from the undiscovered population of about 50 million would be expected to pass almost daily within a lunar distance, and one might strike Earth’s atmosphere about every 10 years on average.
The Catalina Sky Survey near Tucson, Ariz., discovered both objects on the morning of Sunday, Sept. 5, during a routine monitoring of the skies. The Minor Planet Center in Cambridge, Mass., first received the observations Sunday morning, determined preliminary orbits and concluded that both objects would pass within the distance of the moon about three days after their discovery.
Near-Earth asteroid 2010 RX30 is estimated to be 32 to 65 feet (10 to 20 meters) in size and will pass within 0.6 lunar distances of Earth (about 154,000 miles, or 248,000 kilometers) at 2:51 a.m. PDT (5:51 a.m. EDT) Wednesday. The second object, 2010 RF12, estimated to be 20 to 46 feet (6 to 14 meters) in size, will pass within 0.2 lunar distances (about 49,088 miles or 79,000 kilometers) a few hours later at 2:12 p.m. PDT (5:12 pm EDT).