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
Riemannian connection on a surface Riemannian connection on a surface embedded in Euclidean space "E" is just the pullback under the Gauss map of the Riemannian connection on "S". Using the identification of "S" with the homogeneous space SO(3)/SO(2), the connection 1-form is just a component of the Maurer–Cartan 1-form on SO(3). In other words, everything reduces to understanding the 2-sphere properly. For a surface "M" embedded in E (or more generally a higher-dimensional Euclidean space), there are several equivalent definitions of a vector field "X" on "M": The last condition means that the assignment "f" "Xf" on "C"("M") satisfies the Leibniz rule The space