Only hours after the recently found duo of asteroids with provisional designations 2010 RX30 and 2010 RF12 passed the Earth within lunar orbit, another “overstuffed flying couch”, just marginally bigger than 2010 RF12, saw the Earth up close. The object was discovered shortly before 10 UT on September 10 by the Catalina Sky Survey, Tucson, Arizona during their routine monitoring of the skies.
According to the most recent orbital elements, 2010 RK53 passed the perigee of roughly 76,300km at around 23:30 UT on September 8. This time there was no “warning”. The object came in at an elongation of about 34 degrees, i.e. from the direction of the Sun in the sky, where no ground-based telescope can aim (and hope to get any useful results). Therefore, 2010 RK53 wasn’t observed up until it had already gone by. Nevertheless, unlike 2010 RX30 and 2010 RF12, which are now lost in sunlight (at elongation of less than 30 degrees), 2010 RK53 will remain observable by medium and large sized telescopes for a few days until September 13-14.
Although the object had no chance of hitting Earth, a ten 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 ten years on average.