  Communication Faster access than browser!

# Geometric albedo

In astronomy, the geometric albedo of a celestial body is the ratio of its actual brightness as seen from the light source (i.e. at zero phase angle) to that of an idealized flat, fully reflecting, diffusively scattering (Lambertian) disk with the same cross-section. 

## Albedo

Albedo (albedo, meaning "whiteness") is the measure of the diffuse reflection of solar radiation out of the total solar radiation received by an astronomical body (e.g. a planet like Earth).

## Angle of incidence (optics)

In geometric optics, the angle of incidence is the angle between a ray incident on a surface and the line perpendicular to the surface at the point of incidence, called the normal.

## Anisotropy

Anisotropy, is the property of being directionally dependent, which implies different properties in different directions, as opposed to isotropy.

## Astronomical object

An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that exists in the observable universe.

## Astronomy

Astronomy (from ἀστρονομία) is a natural science that studies celestial objects and phenomena.

## Bidirectional reflectance distribution function

The bidirectional reflectance distribution function (BRDF; f_(\omega_,\, \omega_)) is a function of four real variables that defines how light is reflected at an opaque surface.

## Bond albedo

The Bond albedo, named after the American astronomer George Phillips Bond (1825–1865), who originally proposed it, is the fraction of power in the total electromagnetic radiation incident on an astronomical body that is scattered back out into space.

## Diffuse reflection

Diffuse reflection is the reflection of light or other waves or particles from a surface such that a ray incident on the surface is scattered at many angles rather than at just one angle as in the case of specular reflection.

## Ecliptic

The ecliptic is the circular path on the celestial sphere that the Sun follows over the course of a year; it is the basis of the ecliptic coordinate system.

In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy.

Enceladus is the sixth-largest moon of Saturn.

## Hapke parameters

The Hapke parameters are a set of parameters for an empirical model that is commonly used to describe the directional reflectance properties of the airless regolith surfaces of bodies in the solar system.

## Lambertian reflectance

Lambertian reflectance is the property that defines an ideal "matte" or diffusely reflecting surface.

## Opposition (planets)

In positional astronomy, two astronomical objects are said to be in opposition when they are on opposite sides of the celestial sphere, as observed from a given body (usually Earth).

## Opposition surge

The opposition surge (sometimes known as the opposition effect, opposition spike or Seeliger effect) is the brightening of a rough surface, or an object with many particles, when illuminated from directly behind the observer.

## Perpendicular

In elementary geometry, the property of being perpendicular (perpendicularity) is the relationship between two lines which meet at a right angle (90 degrees).

## Phase (waves)

Phase is the position of a point in time (an instant) on a waveform cycle.

## Phase angle (astronomy)

Phase angle in astronomical observations is the angle between the light incident onto an observed object and the light reflected from the object.

## Phasor

In physics and engineering, a phasor (a portmanteau of phase vector), is a complex number representing a sinusoidal function whose amplitude (A), angular frequency (ω), and initial phase (θ) are time-invariant.

## Regolith

Regolith is a layer of loose, heterogeneous superficial deposits covering solid rock.

## Saturn

Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter.

## Solar System

The Solar SystemCapitalization of the name varies.

## Tethys (moon)

Tethys (or Saturn III) is a mid-sized moon of Saturn about across.

## Visible spectrum

The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye.

## References

Hey! We are on Facebook now! »