Today, Neptune's in perfect opposition to the sun, meaning in a straight line with the sun and Earth, and brightest at midnight. It's also at its closest to Earth, and nearing the end of its first orbit since its discovery.

It's pretty amazing to think that it's taken over 160 years for Neptune to orbit the sun once. But it makes sense that the planet was discovered on the last occasion it came this close to Earth, back in 1846. (The opposition happened on August 20 of that year as well, but the planet wasn't discovered until a month later.) Neptune's first full orbit since its discovery won't be completed until 2011, though. Image by NASA/JPL. []