The photograph, taken in 2004 by the Mars explorer Spirit, appears to show a human shaped object that looks startingly like previous photographs purporting to have captured Bigfoot.
Unsurprisingly, conspiracy theorists have had a field day. One blogger wrote: “My first thought: It’s Bigfoot! If you show me another rock in another photo of Mars that naturally looks like that, I will reconsider. “Doesn’t look very much alive though.”
Another added: “These pictures are amazing. I couldn’t believe my eyes when I saw what appears to be a naked alien running around on Mars.”
And one more said: “It’s definitely Bigfoot. That’s why we’ve not been able to find him on Earth, he’s gone to Mars.” advertisement
However not everyone is convinced - one blogger despaired: “Ah, the human eye can be tricked so easily.”
Spirit, sent to Mars to capture images from the surface of the planet, is one half of a $820m (£410m) mission, along with its twin explorer, Opportunity.
It landed on Mars in January 2004 for a three month mission to search Gusev Crater, a rock strewn stretch of soil that scientists believe could be the bed of an ancient lake. If Mars once had surface water, it had the potential to support life.