The Expanse (novel series) a future in which humanity has colonized much of the Solar System, but does not have interstellar travel. In the asteroid belt and beyond, tensions are rising between Earth's United Nations, Mars, and the outer planets. The series initially takes place in the solar system, using many real world locations such as Ceres and Eros in the asteroid belt, several moons of Jupiter, with Ganymede and Europa the most developed, and small science bases as far out as Phoebe around Saturn and Titania around Uranus, as well as well-established domed settlements on Mars and the Moon. As the series progresses,
Orbit of the Moon rearward loops in the Moon's solar orbit. Considering the Earth–Moon system as a binary planet, its centre of gravity is within Earth, about or 72.6% of the Earth's radius from the centre of the Earth. This centre of gravity remains on the line between the centres of the Earth and Moon as the Earth completes its diurnal rotation. The path of the Earth–Moon system in its solar orbit is defined as the movement of this mutual centre of gravity around the sun. Consequently, Earth's centre veers inside and outside the solar orbital path during each synodic month as the Moon