“Irregular satellites collisionally grind really effectively.” Saturn’s Arrakis A good chunk of Saturn’s largest moon Titan is covered in massive dunes. But how they got there in the first place remains a bit of a mystery. Prevailing theories have suggested that organic material formed in the moon’s thick atmosphere, and then rained down to the surface. Now, as New Scientists reports, scientists have come up with a revised explanation. They suggest that the sand may be the crumbling remains of irregular moons that were captured in Titan’s orbit and started colliding with each other, eventually grinding down to dust — an intriguing glimpse into the ancient history of the second-largest moon in the solar system. Moon Cries Southwest Research Institute senior research scientist Bill Bottke and his colleagues observed that the particles found in the moon’s sand dunes were far too strong to be the result of organic materials being created in its atmosphere. The particles that Titan’s moons are made of are also roughly the same size as the particles of the dunes. As a result, the …