Reflectance values express the percentage of light that is reflected back from a surface, the difference having been absorbed or transmitted by the surface.
Definition of AXIAL. 1. : of, relating to, or having the characteristics of an axis.
A planet's axial tilt is a measure of whether the planet is in prograde (the natural direction of rotation of most bodies in our solar system) or retrograde (the opposite, ie, from East to West) rotation. Tilt angle is measured relative to the orbital plane of a planet. A tilt between 1 to 90 degrees is considered prograde rotation (Earth's tilt is 23 degrees, in prograde rotation), a tilt of 90 degrees is considered perpendicular, and neither prograde or retrograde.