For about $250, you can make your very own space-age spy tech, following an MIT professor's instructions.
It can capture high-resolution images of small objects -- like a message written in push pins that had been hidden behind a foam plate.
Take a scenic flight over the summit of Mount Vesuvius in Italy, and the view below is chilling. A dense patchwork of urban sprawl from the nearby city of Naples laps at the flanks of one of the most violent volcanoes on Earth. Since A.D. 79, when Vesuvius exploded with little warning and entombed Pompeii and its 3,000 townsfolk under 15 feet of scalding ash, the volcano has erupted at least 30 times.