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. These new worlds are more alien than anything in fiction. Planets larger than Jupiter with years lasting one week, planets circling the dead remains of stars, others with two suns lighting their skies or with no sun at all. These locations hint at Earth-sized worlds but with split hemispheres of perpetual day and night, waterworlds drowning under global oceans and volcanic lava planets spewing seas of magma. The Planet Factory tells the story of these exoplanets. The specks of dust that circle a young star 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 the life forming on neighbouring worlds or alternatively, can deliver the key ingredients needed to seed its beginnings. It is one of the greatest construction schemes in the Universe and it occurred around nearly every star you see. Each result is an alien landscape, but is it possible that one of these could be like our own home?