Moon



A moon or a natural satellite is a rocky or icy object orbiting a planet. It could be a regular satellite, a moon in a prograde, uninclined and round orbit, these probably formed in the circumplanetary disk (for the Gas Giant or Ice Giant) or from the fragments of a massive impact (for Terrestrial planets). However a rocky planet is more likely to have a Irregular satellite, a moon in a inclined, eccentric or even retrograde orbit, like the two potato shaped moons of Mars, Phobos and Deimos.

Although moons are thought to be boring chunks of rock and ice, it is actually more interesting. First of all, moons can host life, and it can be better than conditions of Garden World, they are protected by the magnetic field of their parent object if they are close enough, and a big moon can either just be warmed by being in habitable zone, or if you want Earth-like conditions far from habitable zone, tidal heating from it’s parent object. Or a far more likely option, a sub-surface ocean warmed by geological activities or tidal forces. Therefore, moons maybe be more habitable than Planets.

Worldbuilding in Practise
One of the icy irregular moon orbiting the Ice Giant Aerope is the famous Apraton, the moon was thought to be a Dwarf planet at once, but then got near Aerope and got captured. Due to the tidal heating, Apraton is heated enough to have subsurface oceans inside, and with the newly discovered “Black Smokers” scientist thought Apraton is ready for life, or maybe it already has life.