These sorted stone circles are found in the Canadian Northwest Territories. They are 5-10 metres in diameter (Image: Agriculture and Agri-Food Canada) A network of sorted stone polygons and circles alongside a flood-carved channel in the Elysium Planitia region of Mars. The sorted circles are generally 15-20m in diameter. This image is a portion of HiRISE image PSP_004072_1845, centered at 4.5 ° N., 156.0 ° E (Image: NASA / JPL / University of Arizona) Close-up of the sorted stone circles shown in the previous image (Image: NASA / JPL / University of Arizona)

STONE circles on Mars are prompting a …