Astronomically, the rings appear to be more like flat ribbons. Why are they at a consistent plane and not orbiting the planet more like a scattered cloud?
Astronomically, the rings appear to be more like flat ribbons. Why are they at a consistent plane and not orbiting the planet more like a scattered cloud?
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An individual object only orbits within a single plane, and objects orbiting in different planes can intersect and collide with each other. Over time, an orbiting cloud is going to collide with itself until the only orbits left are those that don’t collide with each other anymore, and the result is the cloud becomes one big flat disk.
Conservation of angular momentum. You start out with a uniform cloud where each piece of dust or rock is orbiting at its own inclination, but the whole cloud has some average direction of angular momentum. Over time, different pieces will come close and gravitationally interact (or hit each other and electromagnetically interact), and momentum will be transferred between them in a way that leaves them both, on average, a little closer to the average angular velocity of the entire cloud. Millions and millions of these interactions eventually drag the whole cloud into a disk.
This is also more or less what happens to form spiral galaxies, but with stars instead of dust, rocks, or ice.
If you have a cloud of matter in space, each little bit will have its own mass and velocity, and every bit will exert its gravity on every other bit. If you were to measure all of them and took their average, what you’d find is that the cloud as a whole has some angular momentum. That can be described as a plane containing that vector and the center of mass for the system. That plane divides the could into two parts with roughly equal energy/mass/momentum.
So over a long enough period of time those bits of matter will settle into that plane because that’s where the average gravity on either side equals out. And those bits don’t fall all the way into the planet because they have enough velocity to maintain orbit around the center of mass, resulting in a (mostly) flat ring.
Important to note that Saturns rings are not perfectly planar. Just very close.
A band of material orbiting a compact body can only be thick like a cloud if it is kept very hot. The random motions of the particles that make up the cloud will then have large random motions due to the heat.
Saturn’s rings are cold, made of small-ish ice and dust particles. Each particle orbits the center of Saturn, mostly oblivious to the neighboring particles. The reason the orbits of the particles are not tilted with respect to each other is because an orbit that is tilted with regards to the average orbit of the other particles will intersect those orbits periodically, and will eventually collide with other particles. These collisions will change the orbit, and continue until the orbit is no longer tilted. Likewise, the orbit will become circular (even though elongated elliptical orbits are allowed) because an elongated orbit will lead to collisions with particles in neighboring orbits, and the collisions will continue until the orbit is no longer elongated. Over time, collisions cause all orbits to lose their relative tilt, and to become circular.
Saturn looks all fancy with those big, bold rings. If Saturn was the size of a basketball, the rings would be thinner than a sheet of paper. It’s mostly about gravity and motion. The stuff in the rings, ice chunks, rock bits, space dust, they’re all zooming around Saturn in super fast orbits. Because they’re moving so quickly, they kinda flatten out into this giant disc. Like spinning pizza dough. If you toss it just right, it spreads out flat instead of forming a big puff. Also, Saturn’s gravity keeps things in check.
take 1000 little weights and attach them to 1000 strings of different sizes and then attach the strings to the center of a rotating object and you’ll see a good example of why.
gravity pulls everything towards the center of mass. when the mass is rotating that creates a disc area around the middle of the orbital rotation where the gravity is the strongest
When a bunch of objects are orbiting at once, they impact or gravitionally affect eachother until all of the un-aligned objects have beein either ejected, corrected or dropped into the body its orbiting.
This is also why the Solar System is all roughly in the same plane.