Earth's nearest neighbours have turned into uninhabitable hellholes. Understanding their transformation will teach us which rocky exoplanets might be fit for life CLOSE to the sun lie a pair of sizzling coals. You could be forgiven for thinking these strange worlds were two circles of hell: Mercury, a black and blasted plain, and Venus, a sweltering world beset by rain of pure acid. But for all the terror of their outward appearance, their insides are remarkably familiar. Along with Earth and Mars, they form the solar system’s only rocky planets, a stark contrast to the bloated gas giants that make...
