Cydonia (/sɪˈdoʊniə/, /saɪˈdoʊniə/) is a region on the planet Mars that has attracted both scientific[1] and popular interest.[2][3] The name originally referred to the albedo feature (distinctively coloured area) that was visible from Earthbound telescopes. The area borders plains of Acidalia Planitia and the Arabia Terra highlands.[4] The area includes the regions: "Cydonia Mensae", an area of flat-topped mesa-like features, "Cydonia Colles", a region of small hills or knobs, and "Cydonia Labyrinthus", a complex of intersecting valleys.[5][6] As with other albedo features on Mars, the name Cydonia was drawn from classical antiquity, in this case from Cydonia or Kydonia (/sɪˈdoʊniə/; Ancient Greek: Κυδωνία; Latin: Cydonia), a historic polis (city state) on the island of Crete.[7] Cydonia contains the "Face on Mars", located about halfway between Arandas Crater and Bamberg Crater.[4]
Location
Cydonia lies in the planet's northern hemisphere in a transitional zone between the heavily cratered regions to the south and relatively smooth plains to the north. Some planetologists believe that the northern plains may once have been ocean beds,[8] and that Cydonia may once have been a coastal zone.[9] It is in the Mare Acidalium quadrangle.
Satellite picture of Cydonia
Picture of the Cydonia region taken in 2006 by The European Space Agency's satellite Mars Express.
"Face on Mars"
Cropped version of the original batch-processed image (#035A72) of the "Face on Mars". The black dots that give the image a speckled appearance are data errors.[10]
1976 Viking Orbiter image (left, image #070A13) compared with the 2001 Mars Global Surveyor image (right). The "Face" is 1.5 km across in size.
Cydonia was first imaged in detail by the Viking 1 and Viking 2 orbiters. Eighteen images of the Cydonia region were taken by the orbiters, of which seven have resolutions better than 250 m/pixel (820 ft/pixel). The other eleven images have resolutions that are worse than 550 m/pixel (1800 ft/pixel) and are of limited use for studying surface features. Of the seven good images, the lighting and time at which two pairs of images were taken are so close as to reduce the number to five distinct images. The Mission to Mars: Viking Orbiter Images of Mars CD-ROM set image numbers for these are: 035A72 (VO-1010), 070A13 (VO-1011), 561A25 (VO-1021), 673B54 & 673B56 (VO-1063), and 753A33 & 753A34 (VO-1028).[11][12]
In one of the images taken by Viking 1 on July 25, 1976, a two-kilometre-long (1.2 mi) Cydonian mesa, situated at 40.75° north latitude and 9.46° west longitude,[13] had the appearance of a humanoid face. When the image was originally acquired, Viking chief scientist Gerry Soffen dismissed the "Face on Mars" in image 035A72[14] as a "trick of light and shadow".[15][16] However, a second image, 070A13, also shows the "face", and was acquired 35 Viking orbits later at a different sun-angle from the 035A72 image. This latter discovery was made independently by Vincent Di
