const std::set<Body *> &Bodies() const noexcept { return bodies; }
const std::set<Planet *> &Planets() const noexcept { return planets; }
const std::set<Sun *> &Suns() const noexcept { return suns; }
const std::set<Body *> &Bodies() const noexcept { return bodies; }
const std::set<Planet *> &Planets() const noexcept { return planets; }
const std::set<Sun *> &Suns() const noexcept { return suns; }