2010 RF12 and another small asteroid that passed close to earth Wednesday were detected three days before their fly-by, illustrating the improving capability of asteroid-spotting telescopes.
Earth is entertaining two transient visitors on Wednesday – a pair of small asteroids, 2010 RX30 and 2010 RF12, whose track takes them inside the moon's orbit around Earth.
Such close passes have appeared with increased frequency as telescopes and detectors dedicated to asteroid hunting have improved.
That capability holds the promise of improved warnings for potential collisions with relatively small objects that might otherwise seem to come out of the blue. By the time they come close enough to brighten sufficiently to spot, they've almost arrived.
The effects of these small objects on populated areas might be local – they would be too small to be "civilization busters" but too large to ignore, some researchers say – but even a few days' warning can allow evacuations to take place.
Wednesday's objects were much smaller than even those asteroids, and yet they were picked up three days before their fly-by. Although the telescopes and detectors were built to spot much larger objects, they also are proving adept at picking out smaller asteroids.
These survey telescopes "are likely to catch a much larger fraction of objects that could hit Earth than people originally thought," says Clark Chapman, an asteroid specialist at the Southwest Research Institute in Boulder, Colo.