SHEILA TERRY / SCIENCE PHOTO LIBRARY SHEILA TERRY / SCIENCE PHOTO LIBRARY
In this sketch by Leonardo da Vinci, he illustrated the phenomenon of what is now known as earthlight and gave the first explanation of its cause. Earthlight occurs when the shadowed area of the crescent moon is illuminated by reflected sunlight from the Earth. Leonardo thought that it was the seas on Earth which reflected the sun. In reality, the reflectance of clouds is 50% of incident sunlight, that of the oceans only 10%. Comparative luminance measurements of earthlight over time are used to estimate changes in the extent of the cloud cover which are of importance to climate change and global warming studies.
Model release not required. Property release not required.