Forget about rockets to Mars – the future of space science lies with the search for exoplanets. Fifteen years ago, the search for planets – and life – outside the Solar System was a job restricted to science-fiction writers. Now it’s one of the fastest-growing fields in astronomy; more than 4,600 of these ‘exoplanets’ have been discovered to date. There have been some truly stunning recent discoveries, predominantly through the findings of the Kepler Space Telescope, not least the fact that there seem to be planetary systems around pretty much every star. So what are these worlds like? Some of them are mind-boggling – planets that orbit binary stars, giant ‘hot’ jupiters that orbit closer to their stars than Mercury is to the sun, earth-like planets that orbit dying, purple-coloured stars, shrinking planets with tails like a giant comet. The diversity is incredible, and growing. And then of course, there’s the ultimate prize – an earth-sized planet in what's known as the 'goldilocks' zone, the right distance from its star for water to be liquid and, perhaps, for life to occur. Such a planet hasn't been found so far, but it is probably a matter of time. The Planet Factory tells the story of exoplanets and exoplanetary research. It discusses their way planets form, what their structure is and what features they exhibit, and describes in detail the detection techniques used to find them, before looking at what we can learn about surface environments and planetary atmospheres, and whether this hints at the tantalising possibility of life.