Ray system they have been identified on Mars in infrared images taken from orbit by "2001 Mars Odyssey"s thermal imager. Rays appear at visible, and in some cases infrared wavelengths, when ejecta are made of material with different reflectivity (i.e., albedo) or thermal properties from the surface on which they are deposited. Typically, visible rays have a higher albedo than the surrounding surface. More rarely an impact will excavate low albedo material, for example basaltic-lava deposits on the lunar maria. Thermal rays, as seen on Mars, are especially apparent at night when slopes and shadows do not influence the infrared energy emitted
Cerberus (Martian albedo feature) showing no large craters with diameters 500 m superimposed on Western Cerberus Plains lavas indicate the same surface is younger than 49 Ma. Cerberus (Martian albedo feature) Cerberus is a large "dark spot" (an albedo feature) located on Mars and named after the mythical dog Cerberus. The arcuate markings in the upper right are in the Amazonis plains and may be sand drifts. The Elysium volcano, a yellow area north of Cerberus, has several channels radiating from its flanks. The three bright spots, upper left, are volcanoes partially veiled by thin clouds. High resolution images show the bulk of the