Close Encounter of the GPS Kind

An asteroid called 2011 MD and measuring about ten metres in diameter flew by the Earth on 27th June so close that it passed between the Earth and our GPS satellites.

Obviously, it passed by hitting neither satellite nor planet, but I always find any close encounter a little humbling, and a stark reminder that the ‘big one' will eventually come.

To place the fly-by in context, Pasquale Tricarico, a research scientist at the Planetary Science Institute, has created several videos showing the path of the asteroid and how close it came to the GPS satellites.