The moon will be full Thursday, which means we'll see it in all its illuminated glory. But when the moon is just a sliver, we sometimes see our own reflection shining back at us from the moon's shrouded side, in a phenomenon called "earthshine."
Now scientists say the difference in light reflection from the Earth's land masses vs. the oceans can be seen on the moon. By tracking changes in earthshine as Earth rotates, scientists measured brightness variations that correspond to the brilliant, mirror-like reflections from oceans compared to the dimmer reflections from land.
More: http://www.space.com/090407-earthshine-moon.html (http://www.space.com/090407-earthshine-moon.html)