NASA / JHUAPL / CIW

A June 3 image from NASA's Messenger probe shows a scene in Mercury's southern hemisphere, northwest of Magritte Crater. Three overlapping craters form the head and ears of a "Mickey Mouse" shape.

We've had the Face on Mars, the Smiley Face on Mars, even the Elephant Face on Mars — and now we've got the Mickey Mouse Face on Mercury, courtesy of NASA's Messenger probe.

The mousy shape comes from three overlapping craters in Mercury's southern hemisphere, northwest of a larger crater known as Magritte. The biggest crater in this scene, which serves as Mickey's head, measures about 65 miles (105 kilometers) across.

This picture was taken during Messenger's extended mission, with the aim of collecting imagery when the sun is near the horizon. Such conditions produce long shadows that highlight small-scale surface features. The result is that the Mercury mission's mapmakers get a better sense of the lay of the land.

Messenger became the first spacecraft to orbit Mercury back in March 2011, and the end of its one-year primary mapping mission marked the beginning of a one-year extension. Which means we may be hearing more about Mickey, Magritte and their Mercurial friends for months or years to come.

Where in the Cosmos
The Mickey Mouse Face on Mercury was today's featured image for our "Where in the Cosmos" Facebook contest. It took just a couple of minutes for Leslie Kebschull and Brad Perdew to come up with the locale for the cartoonish craters. Their entries came in just three seconds apart. To reward their quick minds and fingers, I'm sending them a pair of 3-D glasses, courtesy of Microsoft Research's WorldWide Telescope. (Microsoft is a partner in the msnbc.com joint venture.)

To get in on next week's contest, click the "like" button for the Cosmic Log Facebook page. And while you're at it, sign up for the Tech/Science email newsletter, which is sent out Monday through Friday. That's a great way to get your daily dose of Cosmic Log as well as other goodies from msnbc.com's Space and Science sections.

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

NASA / JHUAPL / CIW

The first image sent back to Earth from Mercury orbit shows a rayed crater known as Debussy and a smaller crater with unusual dark rays, called Matabei. The picture was transmitted to Earth by NASA's Messenger spacecraft.

Last updated 3:40 p.m. ET March 30:

NASA's Messenger mission unveiled the first picture of the planet Mercury taken by an orbiting spacecraft on Tuesday, and promised to provide more goodies in the days and months to come.

The picture shows a wide region of Mercury's southern hemisphere, including the south pole and a wedge of the planet that has never been photographed close-up before. But you'd probably be forgiven if you wondered whether the Messenger probe was orbiting the moon rather than Mercury: The monochromatic, heavily cratered terrain looks a lot like the lunar surface.

Here's a description of the scene from Messenger's science team:

"The dominant rayed crater in the upper portion of the image is Debussy. The smaller crater Matabei with its unusual dark rays is visible to the west of Debussy. The bottom portion of this image is near Mercury's south pole and includes a region of Mercury's surface not previously seen by spacecraft. Compare this image to the planned image footprint [displayed below] to see the region of newly imaged terrain, south of Debussy."

NASA / JHUAPL / CIW

The yellow square on this mosaic image shows the planned footprint for the first image to be acquired by a spacecraft orbiting Mercury. The dark area represents a region of the planet that has not previously been seen by spacecraft.

Messenger's science team is already familiar with most of Mercury's terrain. The $446 million mission got under way in 2004, and the desk-sized probe zoomed past Mercury in 2008 (twice!) and in 2009. At its closest, Messenger came within 124 miles (200 kilometers) of the surface, which is much closer than the distance from which today's picture was taken (about 9,500 miles or 15,000 kilometers).

But Messenger (whose name comes from the acronym for MErcury Surface, Space ENvironment, GEochemistry and Ranging) wasn't in orbit back then. It was just passing through. The probe finally entered orbit around Mercury on March 17 and is now going through its commissioning phase.

The Messenger mission's principal investigator, Sean Solomon of the Carnegie Institution of Washington, said in a news release that he and his colleagues were "thrilled that the spacecraft and instrument checkout has been proceeding according to plan":

"The first images from orbit and the first measurements from Messenger's other payload instruments are only the opening trickle of the flood of new information that we can expect over the coming year. The orbital exploration of the solar system’s innermost planet has begun."

Today's picture, snapped at 5:20 a.m. ET, was the first of 364 images that were acquired during a span of six hours and sent back to Earth, Messenger's mission team said. More than 1,000 images are due to be taken during the probe's checkout. During Messenger's yearlong science campaign, more than 75,000 pictures are to be sent back.

Mercury has been studied during flybys before, most notably by Mariner 10 in 1974-75, but Messenger is the first spacecraft to orbit the solar system's innermost planet. It's also the densest planet, as well as the planet with the largest daily variations in surface temperature.

Just how big is Mercury's metal-rich core? Do deep, permanently shadowed craters at the planet's poles contain ice? What does its atmosphere (or "exosphere") contain? Why does Mercury have a global magnetic field, while Venus and Mars do not? Messenger's team plans to address all those questions in the year ahead. Some of them may even be addressed on Wednesday, when team leaders are due to discuss Messenger's first images at 2 p.m. ET during a NASA teleconference. Stay tuned for updates after the scientists have had their say. 

Update for 3:40 p.m. March 30: Still more pictures were released on Wednesday, as promised. Check out this Photoblog gallery featuring three of the best images, and check back later for still more about the successful start of Messenger's orbital mission.  

More about Mercury:

• 10 surprising facts about Messenger
• Is Mercury an incredible shrinking planet?
• Mercury just might hit us someday
• Interactive: The new solar system

Join the Cosmic Log community by clicking the "like" button on our Facebook page or by following msnbc.com science editor Alan Boyle as b0yle on Twitter. To learn more about my book on Pluto and the search for planets, check out the website for "The Case for Pluto." And if you want to stay on my good side, don't ever call Mercury the "smallest planet."