Albedo

Albedo is the reflecting power of a planet or a body when light is incident. It is defined as the ratio of light reflected to the light incident on the body. In case of planets, the greater the albedo, the greater is the brightness. The significance of albedo is that it measures the density of the atmosphere on planets. We know that the rocks are poor reflector of light but the atmosphere is a good reflector of light. So, if albedo of a planet is high (i.e. if it seems brighter), this implies that there exists atmosphere on it. For example, very low albedo of the moon, the mercury and the mars implies that they have little atmosphere. Similarly, the earth's albedo is very high; i.e., about 0.35. Venus has the higher albedo; i.e. 0.85. This means the Venus reflects 85% of the Sun's energy.