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Astro*Dictionary by Michael Erlewine





3 articles for "Albedo"

Albedo [Astro*Index]

The total ratio of sunlight reflected by a planet or body compared to what it receives from the Sun. Planets with dense atmospheres have higher albedos than those with no atmospheres.

The albedos of the planets in our solar system are as follows:

Mercury  0.06
Jupiter 0.73
See also:
♦ Brightness ♦ Orb ♦ Rays ♦ Reflection Nebula
Albedo [Munkasey M.]

The percentage of sunlight reflected from a body comparedwith the total amount received from the Sun.

See also:
♦ Brightness ♦ Orb ♦ Rays ♦ Reflection Nebula
Albedo [DeVore]

Literally, whiteness.

A measure of the reflecting power of a planet, in ratio to its absorptive capacity; expressed in a figure which represents the amount of light reflected from an unpolished surface in proportion to the total amount of light falling upon it.

The albedo of the Moon and Mercury is 7; Venus, 59; Earth, 44; and Mars, 15. Thus the changeable character manifested by Moon and Mercury, is seen to be connected in some way with their low reflective capacity.

An entirely different set of Lunar characteristics comes of the fact that as the Moon approaches an opposition to the Sun its surface temperature rises some 70-odd degrees above boiling point, and in consequence it emits a wide band of infra-red frequencies that are several times more powerful than any of the rays it reflects from the Sun. During the first few minutes of a Lunar eclipse the surface temperature falls to a sub-zero level and the infra-red emanation ceases.

The dimly-lit surface of the Moon at the Lunation is due to light reflected back from the Earth, which with its high albedo would appear to the Moon-dweller as four times larger and many times brighter than the Moon as seen from the Earth.

There are some indications that Jupiter emits a ray of its own in addition to its reflected ray, but astrophysicists are not as yet in accord on that point.

See also:
♦ Brightness ♦ Orb ♦ Rays ♦ Reflection Nebula


Astro*Index Copyright © 1997 Michael Erlewine


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