Earthshine

THE WORLD BOOK defines albedo as “the ratio of light reflected to light received by a planet or other heavenly body.” Earthshine arises from sunlight reflected from the Earth to the dark of the moon and back to the nighttime Earth. The albedo is due to the Earth's cloud cover and the diversity of landscapes. Leonardo da Vinci (1452–1519) first explained Earthshine in the 15th century. A simple technique was developed to measure the amount of sunlight that bounces off the Earths surface and is subsequently reflected by the moon. Earthshine is faintly visible to the naked eye on the darker side of the crescent moon as an ashen glow. For many phases of the moon, Earthshine is easily visible by the naked eye.

André-Louis Danjon ...