Scientists Explain 'Scratch Marks' on Mars

No, a giant cat has not been clawing at the surface of Mars, though it might look like that. According to scientists, "scratch marks" or linear gullies on the Martian plains of Hellas Planitia were caused not by life forms but by dry ice—in fact, levitating dry ice. It's not magic: During Mars' winter, carbon dioxide gas in the atmosphere turns solid and is imbedded in the red planet's soil. During summer, the reverse process takes place. 

The deposits break apart and slide over dune slopes, levitating in the process as the dry ice in contact with the warm sediment turns back to gas, per a release. This results in the gullies, which were spotted by the Mars Reconnaissance Orbiter in a 1,400-mile-wide crater deeper than the Grand Canyon, reports CNET.

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