This image shows the dark side of the Moon (insert floyd reference of your choice here). It's a long exposure shot, which explains why the crescent is so bright. But what's being studied is the dark part.
Turns out that the dark side is illuminated by the Earth, reflecting the sun's rays. Looking at that dark area, scientists have found that its darkness varies up to 20% according to season. They've also found that it's dimmer. A brighter dark side indicates a more reflective Earth, which indicates a cooler Earth.
For the last five years the "Earth shine" is down 2.5% which indicates a warmer earth. Global warming? Maybe, but also Sun activity; during the same period, magnetic activity from the Sun has increased from its minimum to its maximum.
But you may want to take all of this with a grain of salt after looking at this bonus image:
This is an actual shot of the Earth and the Moon taken from Odyssey, a spacecraft on its way to Mars. On its way, it is apparently taking pictures of what it's leaving. Odyssey will arrive at Mars on October 24.
Although they say the Moon looks a little smaller than it should, due to some sort of element of photography, I still find the scale surprising.
The dark spot at the bottom of earth is Antarctica.