If gravity works by pulling everything to a single point (planets centre), then what’s keeping the rings on their specific axis? Shouldn’t it be an even layer of debris around the planet?
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The material in the rings has momentum, so it stays in orbit, it could clump together and form a moon. But Saturn is very massive and would apply a large shear force on that moon. That has slowed formation, and maybe prevented it, we can check again in a million years.
Pretty much every astral body in what is known as a stable orbit, has a velocity perpendicular to the largest nearby gravitational pull to keep its distance more or less consistent (sometimes with a periodic cycle/less simple orbit, but still).
Think of the international space station–it is constantly being pulled back down to earth by gravity, but it remains at about the same height because it is travelling sufficiently fast that the earth essentially curves *away* underneath it at the same rate it is being pulled back down.
Saturn’s rings are essentially, dust and rocks and the like with a similar relationship. I believe the “ring” form has to do with a long-timeframe of a debris/dust cloud essentially condensing around a plane of highest mass/rotation. Stuff like that is rarely uniform, and small differences of attractive force/grouping up can cause condensation like that into a rough plane over time. Similar to how most of our solar system also has a rough planar layout (with some variation).
Imagine you start with the debris orbiting randomly. Because the orbits cross, the debris would collide all the time and exchange momentum. Eventually, everything is orbiting on the same plane (the “average” of all planes that stuff originally orbited on).
This is not unique to Saturn’s rings, by the way. All planets orbit the Sun on roughly the same plane, for same reason.
> Why does Saturn have rings? Shouldn’t it be an even layer of debris around the planet?
They probably started that way, but an even layer of material would all be orbiting in different directions as they would all be “pulled to the same point”. Eventually, things “run into” each other enough that everything ends up moving in the same direction. In an orbit, the same direction means a single plane.
This is the same phenomenon that causes the solar system to form into a plane, and all the planets rotate around the sun in the same direction. In this case, the bodies don’t actually have to run into each other, they can “pull” or “grab” each other with gravity, and the process happens the same way.
[This](https://youtu.be/MTY1Kje0yLg?&t=461) famous experiment shows that process. At the very end of the video, you can see the balls start in different directions, but eventually, the collisions cause all but one direction of rotation to slow down and fall into the gravity well.
I believe, unless this has changed, one hypothesis was that the physically material that makes up the rings [which is ice crystals?] came from one of the various moons the planet has.
The moon(s) has/had some sort of “geyser” which is/was spewing water material out into space, caused by the moon itself interacting with the planets gravity pull [causing a stretch type effect on the moon itself, heating up the inner area’s of the moon, causing the ice underneath to liquify and burst upwards once the pressure had built up]. This water then became stuck in orbit around the planet, frozen due to the vacuum of space. And over millions of years, grew to the size they are now.
I hope I’ve explained that correctly
Something collided with something else near Saturn. At first, the debris was a big cloud. Over time, the spin and shape (not a perfect sphere) of Saturn has caused that debris to coalesce around its equator into big rings. Eventually, it will pretty much all fall into the planet like you imagine.
It’s just takes a long time. Also, Saturn is oddly low density, which has the effect of causing this process to take much longer than it would around say Jupiter.
Bc Saturn is in a committed relationship and uses the rings as a symbolism of that commitment.
> What keeps rings on the orbit?
Bits of rock and ice that make up rings are moving at just the right speed. Any slower, and gravity of Saturn will pull them down. Any faster, and they would fly away. But at this speed gravity of Saturn is just right to constantly change angle of their movement and make sure they move around the planet. Kinda like spinning something on a rope. The rope always pulls the thing towards center, but if you spin fast enough, the thing will end up going around.
> Why are they rings?
They probably started as random debris. But debris that are “north” of the equator experience combined pull of all the debris to the south of them. And debris to the south exoerience similar pull in the opposite direction. Over a long time this leads to all debris drifting towards the middle.
Space junk flying around Earth could also form rings someday.
Here you go:
I highly recommend all videos in BBC’s “The Planets” playlist.
It is a single point, but the point is the center of the planet. So anything orbiting around that point is subject to gravity and thus will stay in orbit.
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