why do planets have multiple moons or no moons at all instead of one like earth?
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If a planet is capable of capturing a moon and is in an orbit with moon sized objects it’s very likely going to capture multiple moons. It’s kind of a fluke to only capture one moon.
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Our moons formation seems to be unique compared to the rest of the solar system.
The Moons of the outer planets seem to be planetoids or smaller objects that were formed earlier in the solar system and were captured by the massive planets gravity.
Mars’ 2 moons are likely asteroids from the asteroid belt that were captured by Mars
While our moon was formed when a planet the size of mars struck the primitive earth. Material from this impact formed the moon.
There’s no easy answer to this question because it’s not well phrased. The answer is “things turned out that way for Earth, but Earth’s kinda… strange”.
Stars are huge gravity wells. That means they attract lots and lots of nearby stuff. They have massive clumps of rock and dust and grit and gas that spins around them. Sometimes stuff from outside of the star’s influence comes in and messes stuff up. A lot of times, it doesn’t.
So there’s this chance that, out of all of the billions and trillions of possibilites, something like Earth and its companion Moon pops up around its star.
And there’s a FAR FAR greater chance that out of all the billions and trillions of possibilities, nothing at all like Earth and its companion Moon pops up.
Nobody designed our Earth / Moon / Sun combination. We just got lucky on a cosmic dice roll.
Some say our moon is the result of something colliding with the early earth which is why it’s so big.
Debris coalescing as it orbits a larger body could eventually form several moons or none.
In addition to DarkAlman’s comment, we have very little examples to draw our conclusions from. Our Solar System has only 9 examples (Pluto is a planet dammit, screw you NdGT). We’ve got the following pattern:
– Mercury: 0
– Venus: 0
– Earth: 1
– Mars: 2
– Jupiter: a kabillion (80+)
– Saturn: a kabillion (83+)
– Uranus: 27
– Neptune: 14
– Pluto: 5
We can observe a few things, obviously much bigger planets = more moons, and the inner planets have few moons, probably influenced by the outer planets collecting them.
And Earths moon appears to be unique, not a captured object but a result of a collision. How unique? Well again we only have a handful of examples so its hard to say.
There isn’t a single answer to this question since there are many different reasons why a planet might have multiple moons or no moons at all.
One reason a planet might have multiple moons is if it was formed from the collision of two or more smaller objects. When these objects collide, they can break apart and form into multiple smaller pieces. Over time, these smaller pieces can coalesce and form into multiple moons orbiting the planet.
Another reason a planet might not have any moons is if it is simply too small to hold onto one. A moon requires a certain amount of gravity in order to orbit a planet and remain in place. If a planet is too small, it might not have enough gravity to keep a moon in orbit.There isn’t a single answer to this question since there are many different reasons why a planet might have multiple moons or no moons at all.One reason a planet might have multiple moons is if it was formed from the collision of two or more smaller objects. When these objects collide, they can break apart and form into multiple smaller pieces. Over time, these smaller pieces can coalesce and form into multiple moons orbiting the planet.Another reason a planet might not have any moons is if it is simply too small to hold onto one. A moon requires a certain amount of gravity in order to orbit a planet and remain in place. If a planet is too small, it might not have enough gravity to keep a moon in orbit.
Different levels of orbital stability based on their mass, proximity to Sun, and proximity to other planets.
I suspect that a moon orbiting Mercury or Venus would not be long term stable due mostly to the Sun’s proximity.
For those with many more moons, they have significantly larger mass (and thus more gravity) as well as being significantly further from the Sun. In addition to the Sun causing less perturbance due to distance, the more distance planets orbit the Sun slower, so they have fewer perturbing interactions with the other planets.
Consider looking up the term “Hill sphere” for greater discussion.
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