ESA / DLR / FU Berlin / G. Neukum

A stereo image shows an unnamed crater near Huygens Basin in Mars' southern hemisphere. Look at the image through red-blue glasses to get the 3-D effect.

Mars has some of the highest mountains and deepest valleys of the solar system — but you might not realize that unless you're looking at 3-D imagery of the Red Planet. So put on your red-blue glasses and check out some of the latest stereo imagery from interplanetary orbiters.

First up is today's picture of an elongated crater in the Martian southern hemisphere, as seen by the stereo camera aboard the  Mars Express orbiter. The picture was taken last August but has just been released by the European Space Agency. The crater has all the hallmarks of a cosmic impact, but instead of taking on the usual round shape, it's drawn out as if something struck a glancing blow on the surface.

That's pretty much what scientists think happened: A wider-angle view of the scene shows yet another stretched-out crater off to the north-northwest, directionally aligned with the main crater. That suggests that a train of orbital debris circled inward and hit the surface at a shallow angle. There's other evidence to support that hypothesis, including a butterfly-like splash pattern that spreads out on either side of the crater.

In today's image advisory, the European Space Agency says more of these elongated features will be formed in the future: "The Martian moon Phobos will plow into the planet in a few tens of millions of years, breaking up in the process, and likely creating new chains across the surface." That'll be something for future Mars colonists to watch for ... or watch out for.

NASA / JPL / Univ. of Arizona

A stereo image shows a volcanic vent and the vestiges of lava flows on Mars. Look at the image with red-blue glasses to get the 3-D effect.

Our second 3-D highlight comes from NASA's Mars Reconnaissance Orbiter, or MRO. This geological feature looks similar to the impact crater spotted by Mars Express, but it's the result of a completely different phenomenon. The University of Arizona's Alfred McEwen, principal investigator for MRO's High Resolution Imaging Science Experiment, says this is actually a volcanic vent, sitting on top of a Martian shield volcano.

Lava likely flowed out of this vent repeatedly, with "spatters" of molten rock creating an elevated rim around the vent. "Could these vents be the source of atmospheric methane that has recently been detected on Mars? No, they are old and dusty, like every volcanic vent imaged so far on Mars," McEwen writes in his image advisory.

Such vestiges of Mars' volcanic past could become the focus of future exploration. Astrobiologists speculate that collapsed lava tubes might have provided a haven for microbial communities on Mars, and pit caves on Mars (or on the moon, for that matter) may offer the safest locations for settlements.

NASA / JPL / Univ. of Ariz.

An image captured by NASA's Mars Reconnaissance Orbiter shows light-toned layers in a crater south of Crommelin Crater. Red-blue glasses provide a 3-D effect.

The 3-D image above shows something completely different — the crazy, cratered terrain south of Crommelin Crater, around the Martian equator. The picture, showing the region's light-toned layers, was acquired by MRO last October.

There's lots more to see in 3-D — but if you're looking at these red-blue anaglyphs, you really need 3-D glasses to get the full effect. I believe every household should have a set of the stereo specs lying around. If you're missing out, here's how to remedy the situation: Inexpensive red-blue glasses are generally available at novelty stores, and you may also find them included with 3-D books or DVDs. NASA's website for the STEREO mission provides a list of mail-order outlets, as well as instructions for building your own 3-D glasses.

Here at Cosmic Log, we've distributed hundreds of 3-D glasses that are provided free of charge by Microsoft Research's WorldWide Telescope project. (Microsoft and NBC Universal are partners in the msnbc.com joint venture. WorldWide Telescope's developers have the glasses made up as a promotional item for their astronomy software, which includes 3-D imagery.)

Just today we've given out more than 30 pairs of glasses to folks who "like" the Cosmic Log page on Facebook. If you'd like to keep posted on future giveaways, please visit the page, hit the "like" button and become a full member of the Cosmic Log community.

For still more cool cosmic imagery, in 2-D, check out the latest installment of our Month in Space Pictures slideshow. This week we're featuring the shuttle Discovery's last mission as well as stunners from space telescopes and interplanetary probes. Click on the links below for larger versions of the pictures and additional background:

• Closing in: A perfect lineup for the shuttle and the space station.
• Swirls of ice: Shikotan Island as seen by EO-1 satellite.
• Cosmic reflections: Messier 78 nebula served up by MPG/ESO telescope.
• Pool practice: Bigger version of the AP picture from Star City.
• Continent in the sky: Spitzer's infrared view of the North America Nebula.
• Monster blast from the sun: You'll love this video from the Solar Dynamics Observatory.
• Saturn's northern storm: Planetary Society's Emily Lakdawalla explains Cassini imagery.
• Getting ready for a walk: See more images from Discovery's Flight Day 5.
• Welcomed with open arms: Station's robotic arm grabs Japanese cargo craft.
• Light show: A dazzlingly big picture of Norway's northern lights.
• Ready for landing: Mars Reconnaissance Orbiter sees crater in color.
• Walking on a mock Mars: Simulation crew practices for Red Planet mission.
• A ring of black holes: Chandra and Hubble team up on a galactic pair.
• A grand galaxy: Hubble's majestic view of the galaxy NGC 2841.
• Time to move out: Get a wider perspective on Discovery's preparations for flight. 
• Jumpin' Jupiter: NASA's Jet Propulsion Laboratory explains what smacked Jupiter.
• Remembering Challenger: Learn more about the 1986 Challenger tragedy and its legacy.
• A stunning sight: Italian astronaut Paolo Nespoli rocks the house with his Flickr pics.
• Eyes on the sky: Beautiful vista from the European Southern Observatory.

Still more cosmic views in 3-D:

• Get a fresh 3-D look at Phobos
• See a Martian crater in 3-D
• See a Martian milestone in 3-D
• See the Martian arctic in 3-D
• See more depths of Mars in 3-D
• 3-D delights from Mars
• Still more from Mars in 3-D
• Go on a space mission in 3-D
• See the moon's marvels in 3-D
• Saturn's moons in 3-D
• More from outer space in 3-D
• Fly through a nebula in 3-D
• Cosmic Log's 3-D-O-Rama

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 Alan Boyle's book on Pluto and the search for planets, check out the website for "The Case for Pluto."