MESSENGER images of the Earth

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The MESSENGER spacecraft is currently on its way to the innermost planet, Mercury. It launched in 2004, and will arrive at the tiny planet in 2011. Why so long? Mercury orbits the Sun very quickly, much faster than the Earth. Just getting there is hard enough, but if the spacecraft isn't moving fast enough, Mercury will whiz right past it. So MESSENGER has to change it velocity by quite a bit (how much? Well, that's a bit complicated ^* (hmmm, I'm having trouble getting the anchor linking to work. Scroll down to see the footnote)). There isn't enough fuel on board to do it, so they borrow the velocities of Earth, Venus, and even Mercury itself to get the spacecraft moving rapidly enough to catch up to the mercurial (hahaha! ha!) planet. When MESSENGER flew by the Earth in August of 2005, the engineers back home decided to test ...