On 15 February at 0920 local time, a huge fireball raced across the skies above the Chelyabinsk region of Russia. This meteorite then exploded creating a shockwave that injured more than 1000 people.

The incident was captured on numerous webcams, security cameras and dashcams in the region and these videos were widely distributed on the web.

The following day, Stefen Geens, who writes the Ogle Earth blog, pointed out that these cameras formed an ad-hoc sensing network that had gathered significant data about the trajectory and speed of the meteorite. He used this data and Google Earth to reconstruct the path of the rock as it entered the atmosphere and showed that it matched an image of the trajectory taken by the geostationary Meteosat-9 weather satellite.