Earlier this week, NASA announced that its scientists had discovered a seven-planet solar system orbiting a star named TRAPPIST-1. While “Earth-sized” doesn’t necessarily mean “able to support life,” it’s a good indicator that there are other systems out there that host multiple planets that may be habitable.
For science fiction authors, this is affirmation of a long-standing trope. For decades, authors have imagined solar systems with multiple Earth-like planets that allow for human settlement, providing plenty of space for stories in television and literature. Here are the three big ways writers tell those stories:
Planetary Nation States
The first, major way that inhabited solar systems have been used is as a way to realistically depict a space-faring civilization. Barring some handwaving in the form of faster-than-light-travel, inhabited star systems allow for authors to create a region of space in which they can operate, without having to worry too much about breaking the laws of physics. Characters can board a ship and jet off to the next inhabited planet in the system, which conveniently has its own society and cultures. In many ways, it’s a blown-up version of Earth, only with hundreds of countries.
There are plenty of notable examples from science fiction literature here: K.B. Wager’s The Indranan War trilogy features systems with multiple planets, as do Iain M. Banks’ Culture novel Against A Dark Background, Gene Wolfe’s Book of the Short Sun, several of David Weber’s Honor Harrington novels, and Brian Daley’s Fall of the White Ship Avatar. If you want to squint a little, Kameron Hurley’s excellent novel The Stars are Legion is set in a system of artificial, organic worlds that orbit a central, star-like object.