Unusual fan-shaped features cut into the Martian surface were caused by sulfuric acid "water" exploding from underground and sweeping across the surface of the planet. Yesterday a team of European and US scientists announced this finding, which is based on satellite data from a European Space Agency satellite in orbit around the Red Planet. Want to see the gullies dug by the sulfuric acid up close?

This is the "fan" filled with stair-like formations:

The scientists figured out that it was caused by gushing liquid by setting up an experiment on Earth where they recreated the "gushing water" conditions in a sand bed and observed the structures the water carved out. Here's the Earth experiment:

Images via ESA, NY Times, and Reuters.

Research Explains Origin of Martian Fans [NY Times]