Cydonia is a region in the northern hemisphere of the planet Mars that has attracted both scientific and popular interest because it contains the “Face on Mars” feature. Some planetologists believe that the northern plains may once have been ocean beds and that Cydonia may once have been a coastal zone.
The Viking 1 and Viking 2 orbiters first took images, 18 in total, of the Cydonia region. In one of the images (035A72) taken by Viking 1 on July 25, 1976, a 1.2-miles long mesa, situated at 40.75° north latitude and 9.46° west longitude, had the appearance of a humanoid face. Viking chief scientist Gerry Soffen dismissed the “face on Mars” as a “trick of light and shadow”. However, a second image, 070A13, also shows the “face”, although it was acquired 35 Viking orbits later at a different sun-angle from the 035A72 image. This latter discovery was made independently by Vincent DiPietro and Gregory Molenaar, two computer engineers at NASA’s Goddard Space Flight Center.
Some commentators, most notably Richard C. Hoagland, believe the “face on Mars” and other features, such as apparent pyramids, to be parts of a ruined city — evidence of a long-lost Martian civilization.
More than 20 years after the Viking 1 images were taken, new and better-resolution images of the Cydonia region were taken by a succession of spacecraft, including NASA’s Mars Global Surveyor (1997–2006) and Mars Reconnaissance Orbiter (2006-), and the European Space Agency’s Mars Express probe (2003-).