The latest issue of the journal Nature has a focus on Venus, the hellish twin to our lovely planet. Nine papers reviewing the first major findings from Europe's Venus Express spacecraft reveal that Earth and Venus have a number of remarkable similarities, including size, mass and amounts of carbon dioxide.

Fortunately for us, Earth is a good deal further from the Sun. Because of its close proximity, Venus lost most of its water, its clouds are filled with sulfuric acid, carbon dioxide fills its atmosphere, creating an extreme greenhouse effect, and, of course, it's ridiculously hot on the surface.—Gregory Mone

(Image credit: ESA)

The ultrathin atmosphere, cold climate (average - 67�F), and consequential lack of the liquid water that is required for life make Mars an inhospitable planet. But by 2100, scientists predict, Mars colonists will say goodbye to their spacesuits, thanks to a geoengineering scheme that puts greenhouse gases to good use. The process, called terraforming, employs robots to mine 130 million tons of fluoride and sulfur deposits from Martian quarries each year and transport them to factories.