Earthshine on the Moon
These original Kirt's Cogitations™ may be reproduced
(no more than 5, please) provided proper credit is given to me, Kirt Blattenberger.
here to return to the Table of Contents.
Cog·i·ta·tion [koj-i-tey'-shun] – noun: Concerted
reflection; meditation; contemplation.
Kirt [kert] – proper noun: RF Cafe webmaster.
The amount of
sunlight that is reflected back into space due to clouds, bodies of
water, snow cover, etc., is known as albedo (cloud cover is by
far the most influential). Albedo is a major factor in determining the
global temperature. Measuring albedo has proven difficult in the past,
because the calculations were based on knowledge of the total energy
provided by the sun, then subtracting out the energy accounted for by
the Earth's temperature. Basically, it's the difference between how
hot the Earth would be if it absorbed all of the sun's energy. A novel
new method of measuring albedo has been devised that looks at the amount
of earthshine illuminating the night side of the crescent moon. It is
much more accurate, and does not depend on calculations involving the
Earth's temperature. After 270 days of measurement, a research team
found that the earth is roughly 10% more reflective than the average
during April and May. This means the Earth is significantly cloudier
during those months. NASA's best computer models predicted only a 5%