Can moons have moons?

Easy answer, yes 🙂

But if we think about our solar system, how many moons have moons? Some Asteroids I believe have “moon/s” and of course we have the double dwarf planet system of Pluto and Charon, but other than that?

So we ask, now the question differently, why don’t moons have moons.

Firstly we need to ask basic questions; what is an orbit?

An orbit does not exist :aghast: Ok, orbits exist, but they’re not a pre ordained fact. More they are the result of object “a” being caught in the gravitational well of object “b” whilst still having enough momentum to avoid crashing into object “a”.

We have made this happen ourselves via the ISS.

So we have orbits and now we ask “What shape are orbits?” Well, in some Childrens resource books they are shown to be “Round”, “Circular” orbits.

This is not always/very often the whole truth, orbits usually have some form of elipse and can have wobbles due to other nearby objects.

so lets have a planet (Orbiting a star), a moon and a moon going around the moon.

The moon orbiting the moon would be of a smaller size we assume (Unless laws of physics have gone haywire ;P)

So, we know the Earth and our moon are slowing eath other down and that the Sun can have an additional gravitational effect.

Now we picture our Earth, our moon, a smaller moon and the Sun, and they are all lined up… so they have all the gravity pulling in a particular direction, but then we fast forward and they are all out of allignment, this makes a different gravitational equation.

So, lets step back, orbits don’t exist and gravity is a pulling force and objects have momentum through random events.

So the pull on the smaller moon is going to vary, and with added gravitational equation complexity.

& there we have it, that added complexity just doesn’t lend itself to moons having moons, if a moon had a moon it would likely have an increasingly erratic orbit, causing the smaller moon, to either crash into the nearby planet, crash into the moon (And create rings!!!)(And another blog, explaining more about planetary systems.), or… it could slingshot the planet or the moon and bon voyage.