Albedo and asteroids

by Kay Leather

Albedo is an astronomy term which describes the ratio of the light reflected by a body to the light received by it. Albedo values range from 0 (pitch black) to 1 (perfect reflector). Our Moon has a very low albedo (0.07), while Venus has a high albedo (0.60).

silhouette of person
Photo by Raman deep on Pexels.com

If Earth was an ice world, like Europa, Jupiter’s moon, its albedo would be about 0.84, meaning it would reflect most (84 percent) of the sunlight that hit it. If Earth was covered by a dark green forest canopy, the albedo would be about 0.14 (most of the sunlight would get absorbed). On Earth, changes in ice cover, cloudiness, airborne pollution, or land cover (from forest to farmland, for instance) all have subtle effects on global albedo.

Using satellite measurements accumulated since the late 1970s, scientists estimate Earth’s average albedo is about about 0.30.

NASA Earth Observatory – Measuring Earth’s Albedo

Here is a very beautiful song from the 1980s by Vangelis, called Albedo 0.39.

In our Solar System, the composition of asteroids in the main belt (between Mars and Jupiter) differs with their distance from the Sun. This may indicate different temperatures in different parts of the dust and gas that collapsed to form the Sun and Solar System.

The celestial objects in the asteroid belt have range albedo depending on their composition, some are fragments of larger asteroids that have been smashed apart in collisions and others resemble loosely bound lumps of material akin to gravel.

The Asteroid Belt. Credit: NASA/McREL