The Puppeteers had to make some drastic alterations to their home system, during their history, as waste heat due to overindustrialisation was rapidly making their planet uninhabitable. They moved their home planet further from their sun, to lessen the effects of global warming, but overindustrialisation forced them to move five other planets closer to their world and terraform them into "farming worlds", arranging all the planets into a 'Kemplerer rosette'. (Before Ringworld opens, one of the worlds has left the formation, as part of the central conflict in Niven and Edward M. Lerner's "Fleet of Worlds".)