Clearly, happy people were on Mercury

On September 29, MESSENGER spacecraft passed by Mercury for the third time, flying 141.7 miles above the planet’s rocky surface for a final gravity assist that will enable it to enter orbit above Mercury in 2011. During the encounter, the MESSENGER cameras caught a portion of Mercury's never-before-seen surface . With more than 90 percent of the planet’s surface already imaged, MESSENGER’s science team had drafted an ambitious observation campaign designed to tease out additional details from features uncovered during the first two flybys.

Somebody had to work hard to get this acronym: MErcury Surface, Space Environment, GEochemistry and Ranging. Messenger delivered many nice photos of the surface of the planet, but I like this one the best.

Pretty Pictures

The mission of Atlantis, the shuttle that launched last May to make the final adjustments to the Hubble, is already paying dividends. The shuttle's astronauts installed the Wide Field Camera 3 (WFC3), which snapped this photo of the "Bug" or "Butterfly" planetary nebula.

According to NASA, the star at the center of the nebula first evolved into a huge red-giant star, with a diameter of about 1,000 times that of our Sun. It then lost its extended outer layers. Some of this gas was cast off from its equator at a relatively slow speed, perhaps as low as 20,000 miles an hour, creating the doughnut-shaped ring. Other gas was ejected perpendicular to the ring at higher speeds, producing the elongated "wings" of the butterfly-shaped structure.

Check out the description of this photo and see others at NASA's website.