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Saturn's Rings Formed From Large Moon Destruction
Matt_dk writes "The formation of Saturn's rings has been one of the classical if not eternal questions in astronomy. But one researcher has provided a provocative new theory to answer that question. Robin Canup from the Southwest Research Institute has uncovered evidence that the rings came from a large, Titan-sized moon that was destroyed as it spiraled into a young Saturn."
sorry.
i could live a little longer in this prison
This is a really interesting model and it has a nice ring to it. (And Robin is one of the best researchers I know in this area, so that adds confidence, too.) But can we not use the definite statements in the headlines? This is a model. A good model, to be sure, but just one. I've definitely seen work even recently that makes a comet origin seem plausible, so in the very least, there's a competing model that has to be answered.
Aren't all rings of this nature formed form orbiting debris - debris caused by collisions? The thought that Jupiter will have rings once the conflicting orbits of it's moons finally cause them to collide is not new.. it's expected and assumed that it will happen..
I don't think this is new "science".. seems obvious.
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Esobofh - Currently drinking fresh mango juice.
The theory has been floated but this is the first time that I am aware that someone actually worked out the mechanics of it. It's not 'proof' but it's a lot better than just conjecture.
Disclaimer: I am not an astrophysicist or a planetary expert. It's possible that someone did work out the same thing in detail. If so I just haven't seen it.
It has a nice "ring" to it? Seriously? Be ashamed.
Yes, and t'was a silly place, as you'll recall. Best not to go there.
God liked it, so he put a ring on it.
You need to read more astronomy textbooks.
The same side is facing earth because earth's gravity has absorbed/slowed/negated its angular momentum.
The moon is moving closer to earth, very slowly.
Although it generally accepted that the moon is a product of a collision of a body with earth.
Replying to undo my informative moderation because though correct about the tidal locking, you got the Moon's slow change in orbital distance backwards. It's slowly moving farther away from Earth.
"I zero-index my hamsters" - Willtor (147206)
In 2001, ACC pointed out the odd coincidence between the ring of Saturn being only 4 million years old, and the time when the Monolith appeared on Earth. Hmmmmmm.
BTW - The book has the large monolith at Saturn, not Jupiter. Kubrick was worried about the FX it would take to portray the rings on film, so they changed it to Jupiter.
I'd rather have someone respond than be modded up.
Is this really a new theory? Or is this a new interpretation of an existing theory.
I recently read 2001, finally, and I'm fairly certain Arthur C. Clarke mentions Saturn's rings having been formed due to the destruction of a moon. He's not a scientist, but I'm fairly certain he got the idea from scientific circles.
Not exactly. It was a Mars sized object, and the collision completely demolished it. For a while, the earth had a ring formed from the collision. The ring eventually coalesced to form the moon.
The collision caused the earth's rotation. Ar one time a day on earth lasted three hours. The farther the moon gets from the earth, the more the earth's rotation slows.
I wonder what the sky would have looked like then? The moon would have been HUGE, tides would have been tremendous.
Free Martian Whores!
It's about an inch a year I think. So in 1,000,000,000 years time it'll be 4,000km further away than it is now (assuming, incorrectly probably, that it's always 1" per year, i.e. that the effect doesn't get smaller as it moves away). I'm not sure how far away it has to be to be in danger of escaping orbit entirely though. I expect it's a lot, lot further than that!
We always see the same side of the moon because of tidal locking. It doesn't have anything to do with how the moon formed except in that the impact hypothesis puts the new moon close enough to the Earth that it became tidally locked fairly quickly, but that isn't unique to the impact hypothesis. In very basic terms it works like this:
1) Tides cause bulges on one or both bodies
2) The material that the bodies are made of resists that bulge so the bulge is never precisely where it it 'should' be gravitationally speaking. If the body rotates slower than it revolves the bulge will be behind, faster than it revolves and the bulge will be ahead. Let's say the bulge is ahead in this example.
3) The orbiting body (relative to the tidal bulge) is slightly more attracted to the bulge, since it is slightly closer than the rest of the planet. Since the bulge is ahead this pulls the bulge back (causing the bulging body to slow its rotational speed) and pulls the orbiting body as a whole forward (causing it to increase it's revolution speed).
In the Earth/Moon system, this has locked the moon's rotation rate to it's revolution rate. The same isn't (yet) true for the earth, if you stand on the moon you will see all sides of the Earth. However, that is very, very slowly changing. Each trip around the planet, the moon steals some of the Earth's rotational energy and turns it into orbital energy, raising the orbit of the moon a tiny bit and lengthening the day a tiny bit.
The collision caused the earth's rotation. Ar one time a day on earth lasted three hours. The farther the moon gets from the earth, the more the earth's rotation slows.
I think you're confusing two things, here. The collision did almost surely affect the Earth-Moon system's total angular momentum, but the early spin rate and the gradual slowing of the Earth isn't due to the collision (except indirectly), but due to tides transferring angular momentum from Earth to the Moon.
We really don't know Earth's initial spin state since there's no way to find that in any sort of record. (At least none I can think of. It just doesn't leave much of a mark.)
I will believe this when I see the CGI video of a moon exploding as it spirals into Saturn.
In the very distant future, it'll be flung out of orbit.
No, it won't. I'm not sure that's ever energetically possible, let along possible from an angular momentum, standpoint. The Moon will evolve away from Earth until it's around 90 Earth-radii away (it's around 62 right now) and then halt its motion when we're in the double-locked state, like Pluto and Charon. At that point, solar tides take over and slow the Earth down more (but slower) and shift the geosynchronous orbit outside of the Moon's position, at which time the Moon starts moving back toward the Earth. But this is about 50 billion years away, and...
However, this will be long after the Sun goes nova.
No, it won't. Unless our models of stellar evolution are way, way wrong, the Sun's not a candidate to explode in any way. It'll swell up and then shrink and cool into a white dwarf. It may or may not destroy Earth in the process. (Odds favor "destroy Earth", but models differ.)
This is a really interesting model and it has a nice ring to it. (And Robin is one of the best researchers I know in this area, so that adds confidence, too.) But can we not use the definite statements in the headlines? This is a model. A good model, to be sure, but just one. I've definitely seen work even recently that makes a comet origin seem plausible, so in the very least, there's a competing model that has to be answered.
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Well, I read all the comments so far and nobody has discussed the actual new parts of the model. The novelty is that the destroyed moon is assumed to be differentiated (The heavy metal and rock fall to the core and the light ices stay on the surface.) and Saturn was in its very early stages, when it was hot and its atmosphere greatly distended. This means that as the moon spirals in toward Saturn, its icy mantle gets stripped off by tidal forces first. That makes a vast disk of icy material from which the inner icy moons and the ring system are formed. Since the denser rocky material at the core of the moon is less affected by tidal forces, it impacts the extended atmosphere of Saturn and gets swallowed up before it has a chance to contribute to the disk. This explains the composition of the rings and moons better than previous models.
The point is not that it was a moon. There was no collision. Takeaway point if tl;dr:
The rings were formed by tidal disruption of a moon with an icy mantle and a rocky core.