CYDONIA
(the face on mars)

The original images, taken by the Viking spacecraft lead to questions about the origin of the feature. A few ideas and theories arose speculating that the features may have been built by aliens in the distant past. These theories are based largely on the results of computer photo enhancements and other analytical techniques performed on the Viking images beginning in the early 1980s. However, most planetary geologists agree that erosion and "marsquakes" are responsible for the formation.

Above: This image compares the original Viking image (left) to an image taken by Mars Global Surveyor (middle and right). The MGS images have been scaled to approximately the same size as the Viking image. The middle image is shown as taken by MGS, and is shown to the right with contrast adjusted to simulate the lighting conditions of the Viking image.