# Astronomical Albedo

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The Astronomical Albedo calculator computes the astronomical albedo from the absolute magnitude of the object and the diameter.

INSTRUCTION: Choose units and enter the following:

• (H) Absolute Magnitude
• (D) Diameter

Astronomcial Albedo (A): The calculator returns the albedo as a real number.

#### The Math / Science

Albedo is latin for whiteness.  In astronomy, albedo is the measure of the diffuse reflection of light from a star (e.g. our Sun) of solar radiation compared to the total solar radiation received by an astronomical object (e.g. the Moon).  The Albedo (absolute magnitude and diameter) or reflection coefficient is the diffuse reflectivity or reflecting power of a surface. It is the ratio of reflecting radiation from the surface  to incident radiation upon it. Its dimensionless nature lets it be expressed as a percentage and is measured on a scale from zero for no reflection of a perfectly black surface to 1 for perfect reflection of a white surface.

The formula for astronomical albedo is:

A=((1329·10^(-H/5))/D)^2

where:

• A = astronomical albedo
• H = absolute magnitude
• D = diameter in kilometers

## References

Wikipedia (https://en.wikipedia.org/wiki/Albedo)