Hi solar system makers!

I recently received a question in the official game email makeyoursolarsystem@gmail.com about how to create moons or natural satellites:

I have been tinkering with the game for a couple hours now, and I’ve made nice stable systems, but I am having trouble creating moons that remain near the planetary body. They either move too fast, too slow, or drop into a higher/lower orbit, and later get destroyed. Any suggestions on making a stable lunar body (ideally like in the app’s preview pictures)? Thanks for any assistance!

By Hunter Poston.

Thank you again Hunter for your interest in the game! And it is a very interesting question as I am sure other players are also struggling with this. This was my answer to Hunter and I hope it is useful for more players:

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[…] About the moons, how are you exactly trying to create them? I will explain a couple of tricks. Think in three simple objects: star, planet and the moon you try to create.

The main thing, (probably you are already doing it): always select and follow the body (with the camera button) you are trying to get orbited. The initial movement of the object you are creating, even if the arrow has zero length, is relative to the tracked object. So even if the planet it’s orbiting a star, you don’t have to compensate the movement of the planet.

Next, keep in mind that gravity is “real” in the game, in the sense of mass, speed, intertia, etc. Gravity decreases with distance squared. But distances in the game are so short (in real life objects are very far away). It has to be in this way because if not, the game is not playable as objects are not in camera, being boring having to zoom in and out and not seeing all at same time.

Also, in real life, the distance planet-moon is super close compared to the distance planet-star (can be from 400 to 5000 times closer). In the game sometimes is just 5, 20 times.

As distances are really short, the moon is going to be very perturbed by the star. How to prevent that?

– Decrease the star-planet mass relation. In other words: try having a planet not very small and a star not so so big. For example, an orange star with a jupiter or super-jupiter works better than a blue star with an earth-like planet (again, because we want to increase the attraction from the planet -to the future moon- and decrease the attraction from the star).

– Increase the distance planet-star. In that way, the moon will be less perturbed by the star.

– Reduce the distance moon-planet, just for same reason than above. The moon will be more confined around the planet, less perturbed.

Even in real life, this “works” (generally speaking). Inner low-mass planets don’t have moons  (earth is rare in that aspect). Far big-mass planets have lots of moons. 🙂

And one last trick. Try to create the moon in the opposite direction than the planet is orbiting the star. If the planet goes clockwise, try to create the moon counter-clockwise and viceversa. This will prevent gravitational pulls.

Last, even if is obvious, the planet orbit should not be near other planet orbit, wich could attract a little the moons.

Summarizing, if you want a perfect habitat for moons:

1. Create a low-mass star, like red or orange.
2. Select a high mass for the planet, like Jupiter or similar.
3. Create the planet far away from the star in a stable circular orbit, without other big planets near.
4. Select Camera and track the planet, zoom in.
5. Optional: if you want more than one moon, select a very low mass for them. In that way they will not perturb each other. If not, even an earth can orbit a super-jupiter (althought this is more a double planet…)
6. Create the moon very near to the planet in the opposite direction than the planet is orbiting the star.
7. Optional: if you want more than one moon, continue doing 6), in higher orbits, until it’s so far than the planet can not attract more. Also, same direction than other moons. (For planets around a star, is better to have opposite directions in adyacent orbits -even if this is less realistic-, as they are less time near each other when they cross, and therefore they perturb less each other, but this small moons don’t have almost any attraction).