Twenty years ago, the search for planets outside the Solar System was a job restricted to science-fiction writers. Now it's one of the fastest-growing fields in astronomy with thousands of exoplanets discovered to date, and the number is rising fast.

These new-found worlds are more alien than anything in fiction. Planets larger than Jupiter with years lasting a week; others with two suns lighting their skies, or with no sun at all. Planets with diamond mantles supporting oceans of tar; possible Earth-sized worlds with split hemispheres of perpetual day and night; waterworlds drowning under global oceans and volcanic lava planets awash with seas of magma. The discovery of this diversity is just the beginning. There is a whole galaxy of possibilities.

The Planet Factory tells the story of these exoplanets. Each planetary system is different, but in the beginning most if not all young stars are circled by clouds of dust, specks that come together in a violent building project that can form colossal worlds hundreds of times the size of the Earth. The changing orbits of young planets risk dooming any life evolving on neighbouring worlds or, alternatively, can deliver the key ingredients needed to seed its beginnings. Planet formation is one of the greatest construction schemes in the Universe, and it occurred around nearly every star you see. Each results in an alien landscape, but is it possible that one of these could be like our own home world?
20年前，寻找太阳系外的星球仅仅是科幻小说作者们的工作。如今这工作已经成为了天文学中发展速度最快的领域之一，所发现系外行星达数千颗，且数量尚在快速增长。

这些新近发现的世界比科幻小说所描述的一切都要新奇。比土星更大的星球，一个地球周就已过了数年；有些星球的天空中挂着两个太阳，或者有些直接没有太阳；有金刚石地幔的星球上流着焦油的海洋；有近似地球尺寸的星球，被分为永昼和永夜的两个半球；有浸在全球性海洋下的水下世界，有熔岩海洋肆虐冲刷的火山熔岩星球。这缤纷多彩的发现仅仅是个开头。还有一整个银河系的可能性在等待。


星球工厂讲述了这些系外星球的故事。每一行星系统皆有不同，但一开始大部分（如果不是全部）年轻的恒星都会被尘埃云围起来，尘埃、斑点以粗暴堆砌的方式聚集，能够形成尺寸数百倍于地球的巨大星球。年轻星球不停变换的运行轨迹毁灭着邻近星球正在演化的生命，或相反地，能够为邻近星球输送生命起源所需的关键养分。行星形成是宇宙中最伟大的构建方案之一，而且它发生在目光所及的几近每一星球中。每一次形成都带来一种外星景观，但是否有可能，在这些景观中存在一种正好与我们的家园星球相似？