I thought I'd go with an astronomy/sci-fi theme today and for the next two Fridays :)
Albedo \al-ˈbē-(ˌ)dō\: : reflective power;
specifically : the fraction of incident radiation (as light) that is reflected by a surface or body (as the moon or a cloud)
Etymology: Late Latin, whiteness, from Latin albus
First Known Use: circa 1859
"And, second, the planet varied in brightness substantially over the course of its twenty-nine-hour-and-seventeen-minute day. The reason was easy to deduce: most of one hemisphere was covered with land, which reflected back little of Tau Ceti's yellow light, while the other hemisphere, with a much higher albedo, was likely covered by a vast ocean, no doubt, given the planet's fortuitous orbital radius, of liquid water — an extraterrestrial Pacific."
(From "On the Shoulders of Giants" by Robert J. Sawyer)