Let's say you have a planet about the size of Earth. It has three moons, each roughly the mass of one-third of the Earth's moon. Would this cause tides of different magnitude than those on Earth? Are there other ways in which this would affect the world?

  • 2
    $\begingroup$ Tidal forces depend very strongly on the distance between the planet and the moon. They are inversely proportional to the cube of the distance. So then, it is rather important to know the distances between the planet and those three moons. $\endgroup$
    – AlexP
    Commented Apr 4, 2020 at 18:29
  • $\begingroup$ You need to be careful where you place the moons or there orbits will not be stable over geologic timescales. If you aren't careful, one or two may be flung out of the system. $\endgroup$
    – Ryan_L
    Commented Apr 4, 2020 at 19:04
  • $\begingroup$ do you actually mean "effect" or rather "affect"? $\endgroup$
    – ths
    Commented Apr 4, 2020 at 20:59

1 Answer 1


Moons will be in a stable and resonant orbit, like the three first galileans.

Gravitational pulls will be weaker, even when the three moons are aligned due the distance to the planet compared than that pull of the Moon.

Nights will be darker than in Earth due no a full moon to reflect much light, that may make the nocturnal fauna are less dependent of eyesight, or still more specialized.

A civilization formed in your planet will have some nice ways to build calendars.


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