NASA's astronauts are stepping up their already aggressive and savvy use of Twitter by posting images of their view of planet Earth, from the space shuttle. In particular, Soichi Noguchi - the most prolific of all the astronauts on board, according to Mashable - has snapped more than a few more gorgeous Twitpics, including a vivid aurora created by a geomagnetic storm.

Noguchi flew to the ISS on December 20, 2009, and he's scheduled to return in June 2010, Mashable says. He's published 1,000 tweets and accumulated around 174,000 followers.

Of all the government agencies, NASA is arguably the most aggressive in its use of Twitter and other forms of social media - in no small part in order to raise awareness of its missions. It has held several tweetups and last year gave 100 Twitter users front-row seats at the Kennedy Space Center for the Nov. 16 liftoff of the space shuttle Atlantis - propelling the US space agency into the stratosphere of trending topics the day before the launch. The 100 tweeters, also known as tweeps, attracted more than 150,000 followers, making the event the third-most-popular topic for the day. In an experience usually reserved for more traditional media, the tweeps also received behind-the-scenes tours of the space-center facility and spoke with NASA astronauts, technicians, engineers and managers.