National Geographic: Earth's Evil Twin (2010)
Millions of years ago, Venus and Earth cut similar figures. Roughly the same size and about the same distance from the sun, their respective evolutions could have followed similar paths. But today, Venus is a seething vision of Hell, its battery-acid atmosphere and incessant, hurricane-force winds masking a blistering volcanic surface. Some scientists wonder if it is a harbinger of what's in store for Earth.