At www.popularmechanics.com/space/a22619/earth-narrowly-missed-by-asteroid/ … is another link provided by William Thompson. This concerns a small cosmic body that went unseen until it was one quarter of the distance from the moon – but passed by without incident. It was reported at www.spaceweather.com during the same week (last week of August 2016) but it is remarkable that sizable pieces of space rock can come that close to the Earth without being picked up by the many cameras and telescopes scanning the sky. This is reminiscent of the 2013 Chelyabinsk meteor that went entirely unseen by astronomers until it got tangled up in our atmosphere. They had their eyes trained on another space rock that had passed by a day or so earlier – and was much bigger. The current offending asteroid (or comet remnant) was dark and on an elliptical orbit (therefore not easily spotted).