* Astronomy

Explosive crater twins on Mars

Dramatic underground explosions, perhaps involving ice, are responsible for the pits inside these two large martian impact craters, imaged by ESA's Mars Express on 4 January.
The 'twin' craters are in the Thaumasia Planum region, a large plateau that lies immediately to the south of Valles Marineris, the largest canyon in the Solar System.
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