[aeon10]

Couldnt it have been wind? or is the whether on mars really calm.

[ksmiley]

Mars does have wind. In fact, dust storms have been known to last for weeks and encompass nearly the entire planet.

However, I don't think the wind is a likely culprit. If the wind was strong enough to knock over a rock, it would also be strong enough to blow a lot of dust around. That would be very noticeable to anyone watching the rover's feed, and would surely have been mentioned in the article.

[cjensen]

The atmosphere is very thin, so even a fast wind doesn't push much.

[m3mnoch]

probably not since all the other rocks (many an order of magnitude smaller) are still in their same places.