In 1976 the Viking Orbiter radioed back many images from Mars. Among those form the Cydonia region, one depicted a rock formation that strongly resembled a human or humanoid face staring straight up into the heavens.
You can probably guess what was made of this… ‘Pareidolia’ is the term for neurological or psychological phenomena where vague images are interpreted by the brain as specific images. Statistically speaking, it is a type I error, a “false positive”.
A nice article “Paranormal Phenomena: The Face on Mars: Once and for All” contains some background material on the ensuing kerfuffle, including links to large NASA images of the entire regions photographed.
In 1998, the Mars Global Surveyor (MGS) reached the Red Planet with far better, more high-resolution equipment than Viking had carried. Initially, NASA had not planned to re-map the Cydonia region, but public outcry was so great that in April 1998, the MGS was programmed to re-photograph segments of the Cydonia region, including at least one of the face (there was also something on ‘pyramids’ there which we will not cover here). If you move the mouse over the adjacent figure (or tap it), the newer photo appears, shifted and rotated to match the one taken 22 years earlier. You can judge for yourself whether you interpret this as a face – about 2.5 km tall, 2 km wide and about 0.5 km of height – staring right out into space…
Of course, none of the inevitable conspiracy theories was quenched by the new image.
We have a very strong tendency to see patterns in noise – which is often just fine, as seen here.
In early 2006 a new face was found in Peru [GoogleMaps, Register article]
And in October 2006 an Indian with an iPod… GoogleMaps
More: Holy Toast…
More on Pareidola at The Sceptics Dictionary