ANTOINE LABEYRIE has a dream. He wants to photograph tropical forests, mountain ranges, oceans and deserts, but the Amazon, the Himalayas, the Pacific and the Sahara leave him cold. Instead, he has his sights firmly set on the clouds and continents of worlds many light years away from Earth. Sitting on Labeyrie’s drawing board are plans for a hypertelescope, a new breed of space telescope that is capable of mapping distant cousins of Earth in exquisite detail.
Measuring hundreds of kilometres across, these hypertelescopes will be large enough to resolve a green patch the size of the Amazon basin on an alien world 10 light years away. Such images could tell us about the sway of the seasons – clinching evidence for life on planets outside our solar system.
It is a remarkable prospect. Twenty years ago, nobody even knew about the existence of “exoplanets”. The first one, orbiting a sun-like star known as 51 Pegasi, wasn’t discovered until 1995. It bears little resemblance to Earth: the planet (nicknamed Bellerophon by its Swiss discoverers, Didier Queloz and Michel Mayor of the Geneva Observatory) is a bloated ball of hot gas whirling around its parent star every four days. Since then, over 160 massive exoplanets have been found in more than 100 planetary systems.
Even though none of them look like our own solar system, most astronomers are convinced that Earth-like planets must be fairly common – just incredibly hard to find using today’s techniques. The smallest found so far appears to weigh 5.5 times as much as Earth (Â鶹´«Ã½, 28 January, p 12), but now two missions are aiming to…
