Martian rock mystery solved.

Last month NASA’s Opportunity rover team spotted a rock which suddenly appeared next to the Mars rover. The mystery has since been solved, with the finding that it had been kicked there by the rovers tyres.

“Once we moved Opportunity a short distance away… we could see directly uphill an overturned rock that has the same unusual appearance," said mission investigator Ray Arvidson of Washington University. "We drove over it. We can see the track. That’s where Pinnacle Island came from.”