
The Pacific Ocean seen from space a cozy spot for extraterrestrial microbes to land. Image from Michael Benson's new book, 'Planetfall.'
The fireball bearing down on the little town of Tata, in southwestern Morocco, in July 2011 was like nothing the locals had ever seen. There was one sonic boom, then another as a yellow slash of fire cut across the sky. The yellow turned to a landscape-illuminating green, the fireball split in two, and a hail of smoldering rocks crashed to the ground across the surrounding valley. With that, the planet's latest invasion from Mars was over.
Scientists quickly pounced on the incoming ordnance, dubbed the Tissint meteorite after the type of rock it was made of. They wanted to know...