Gordii Dorsa

Image of the Day explores Mars nomenclature. Gordii Dorsa = Dorsa: ridge. Gordii: the Gordian knot, this complex knot was tied to King Gordius of Phrygia's chariot. An oracle said that whomever untied the knot would be the next king of Asia. Alexander the Great cut open the knot with his sword. Gordii Dorsa is one of the largest ridges on Mars. The outlined area shows the margins of the dorsa on this daytime IR image. The area between the arrows is the dorsa, which rises above the surrounding plains. Gordii Dorsa is an area of intense study, as we are not yet sure how this ridge was formed. The surface of this ridge is undergoing erosion by the wind, which indicates that the material that makes up the ridge is not solid rock. Nomenclature Fact of the Day: Some mythological accounts say that Zeus was hidden in a cave on Mt. Ida after his birth, so craters on the asteroid Ida are named for caverns and grottos all over the world.