Within the space of less than an hour on September 5, the Mount Lemmon Survey discovered two objects which will both pass by the Earth on September 8 at a distance closer than the Moon! This unprecedented coincidence provides an exciting observing challenge for amateurs although those observing from the UK will not have the best views. The intrinsically smaller object, 2010 RF12, will be the more favourable observing target in that it passes closest at about 0.21 lunar-distance, i.e. about 80,000 km. Tonight from the UK (Sep 6/7) this object will be 17th magnitude but by tomorrow (Sep 7/8)...