Is space structured like a flat plane where all planets align along a single y-axis, or is it akin to an expansive ocean where planets occupy positions across multiple axes?
In: Planetary Science
The planets around our sun mostly share an axis, because of how the solar system formed from a cloud of debris. So at least locally it’s a flat-ish plane. As we move farther out more distant objects no longer follow this plane as they have not been influenced strongly enough by the gravity of the other bodies in the plane.
But the next solar system over will have its own, different plane. All of the solar systems in the milky way likewise orbit on roughly the same plane.
So there is no universal plane, but things in space do tend to take on planar shapes.
This is a deceptively good question; what it’s asking, in essence, is if there’s anything inherent to the nature of space where all the planets experience “flat” orbits relative to the *plane of the ecliptic* — the two-dimensional plane that contains the orbit of the Earth around the Sun.
The answer is actually no; the plane of the ecliptic is different from the average of the planets’ orbits by 1.6 degrees; the most significant deviation is Mercury’s orbit, which is off by 6.3 degrees.
The reason the orbits are *relatively* flat is because the angular momentum of all the material that made up the early solar system ended up canceling out and pushing everything into a ring, much like pizza dough spreads into a disk when it’s tossed.
https://www.discovermagazine.com/the-sciences/giving-a-side-eye-to-the-solar-system
A helpful way to think about gravity and how it influences masses in the solar system is to think of a kitchen sink. Imagine that the sink is filled, but slowly draining. The water spirals around the drain, but it’s not some sudden change in the fluid motion denoted by an event horizon, water outside of the initial spiral will experience inertial effects. The closer the water to the spiral, the faster it seems to move, the further out, the slower the rotation.
Similar to fluidic inertia, mass moves and mass attracts, and inevitably mass will coalesce to the point where its own gravitational pull can noticeably influence the trajectory and speed of foreign objects. Over millions of years it’s only natural the nearest large objects would fall into a similar planar axis, much like how metronomes on a shared unstable surface can effectively synchronise.
Everything is pulling everything else and the heaviest nearest stuff in our solar system moves in one direction, which in turn causes neighbouring stuff to move in a similar direction, like geese flying in a V.
Planets are generally in a plane. Best way to think about it is to imagine long time ago a cloud of debris orbiting the sun across many different planes. Eventually (billions of years) they collide enough that the stuff that’s left is generally in a plane and can’t collide anymore.
Planets do orbit in different planes. But they tend to be close to just one plane, so the drawings of the solar system you see are pretty much correct.
This is because a solar system forms from a big cloud of matter. Once enough matter collects in one place it will collapse inward due to gravity. The matter at the center of the collapse becomes the star. But because the collapse is not completely neat and symmetric a lot of the matter will not collapse directly into the star, but instead fall into orbit around it. This matter eventually becomes planets and asteroids and things.
The matter initially orbits in many different planes. But eventually it averages out into a single plane as all the different bits clump together or collide. Similarly a lot of the matter averages into a nearly circular orbit as opposed to being more elliptical.
The planets are the result of all that clumping and colliding. But notably smaller objects like asteroids and comets are less likely to end up in orbits in that same plane. They can appear in any plane and generally have more elliptical orbits. They escaped most of that clumping and colliding when the solar system was formed.
Similar things happen at the galactic scale which is why we see lots of spiral galaxies that are mostly flat.
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