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What is between the asteroid belt and the Kuiper belt

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orienteer

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I am wondering why such a large area would be mostly empty. My guess is that Jupiter and the Sun have a combined gravity strong enough to clear the area. Once the objects are inside of Jupiter's orbit, Jupiter and the sun would cancel each other some. That said, shouldn't Saturn and Uranus be approaching the Sun, since their mass would be higher than any asteroids nearby? Surely when Jupiter transits Saturn, there must be a deviation in Saturn"s orbit.
 
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bdewoody

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I think four large gas giants are adequate to keep most objects out of the area between the asteroid belt and the Kuiper belt. Afterall one of the requirements for being classified as a planet is the the planet keeps it's path clear, or something like that.
 
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MeteorWayne

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Why would Jupiter's gravity cancel that from the sun? When Jupiter's on the same side as the outer stuff (planets and TNO's) the gravity adds together. When it's on the opposite side of the sun, it's 15 AU away.

There are asteroids called Trojans in about the same orbit as the giant planets but ~ 60 degrees ahead and behind near the L4 and L5 LaGrange points.

There are asteroids called Centaurs that reside in that area between Jupiter and Neptune, but their orbits are long term unstable because of the gravity of the Giants. The planets themselves are relatively stable at this time because they have so much momentum in their current orbits.

That said, every object in the solar system (even the sun) has it's orbit constantly changed by the gravity of all the other objects in the solar system. The planet's orbits are not the same on each trip around the barycenter (center of mass of the solar system) so any description of the orbit is "just for now" as the elements constantly change. That is why they are called "osculating" orbits.

Hope that helps.

Wayne
 
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orienteer

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Meteor Wayne wrote:

Why would Jupiter's gravity cancel that from the sun? When Jupiter's on the same side as the outer stuff (planets and TNO's) the gravity adds together. When it's on the opposite side of the sun, it's 15 AU away.

I think you may have misread my post. When the asteroids pass Jupiter's orbit, IE enter the asteroid zone, they would have a outward tug from Jupiter every 15 years or so that would negate some of the constant tug of the Sun.

On a parallel thought process, once the asteroids pass the Martian orbit they must accelerate towards the Sun. If I am right, I would think that most asteroids would be beyond Jupiter's L1.
 
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MeteorWayne

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I think you're confused about the structure of the asteroid belt. Pretty much, the asteroids there have been there since the beginning of the solar system. Very few (<1%) of the asteroids in the belt have migrated there in the last few billion years. (There is a suggestion of a small number of asteroids in the very outer belt that moved in during that time)

Asteroids that cross Jupiter's orbit from outside are very rare (in fact they are usually comets) and are on highly eccentric orbits, spending only a small part of their orbit inside Jupiter. When Jupiter gives them the right tweak at the right time, they become what are called Jupiter family comets. There are about 20-100 of them at any time, and the typical lifetime is less than half a billion years; about 6% wind up hitting the sun (or a planet), the rest are ejected from the solar system by interactions with Jupiter.

"On a parallel thought process, once the asteroids pass the Martian orbit they must accelerate towards the Sun."

Why? They continue on in their orbit. The sun isn't a vacuum cleaner, it's just a bit of mass, part of what any object orbits around.
 
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EarthlingX

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http://www.universetoday.com : Trojans May Yet Rain Down
Oct 5th, 2010

by Jon Voisey



It would be an interesting survey to catalog the initial reactions readers have to “Trojans“. Do you think first of wooden horses, or do asteroids spring to mind? Given the context of this website, I’d hope it’s the latter. If so, you’re thinking along the right lines. But how much do you really know about astronomical Trojans?
...
In the past decade Neptunian Trojans have been discovered. By the end of this summer, six have been confirmed. Yet despite this small sample, these objects have some unexpected properties and may outnumber the number of asteroids in the main belt by an order of magnitude. However, they aren’t permanent and a paper published in the July issue of the International Journal of Astrobiology suggests that these reservoirs may produce many of the short period comets we see and “contribute a significant fraction of the impact hazard to the Earth.”
...
 
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CalliArcale

Guest
There is one other important observation -- just because a space appears to be empty does not mean that it is. There are known small bodies orbiting between Jupiter and Neptune, but they are very hard to spot. Many are quite dark, and being so distant from the Sun, there is less light to illuminate them. They are also very far away from Earth, and move quite slowly against the backdrop of stars because of their large orbits. There is also a great deal of space for them to be in. Put all of these factors together and finding them is harder than finding a needle in a haystack. But it's not impossible, and there are people dedicated to precisely that. More and more of them are spotted every year, and it's looking as if that space is not so empty after all. (Note, however, that "not so empty" is relative; even the main belt of asteroids has an awful lot of empty space between things.)
 
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