Is the Asteroid Belt really the remants of an unformed planet, or...?

Question

Has there ever been serious research or theoretical discussions as to whether or not it could have actually been a complete planet that suffered a cataclysmic collision with a rogue planet or planet-killer asteroid?

Answer 1

That theory, though once favoured, is now discredited. The view now held is not that a planet was shattered by a collision but that no planet was able to form, because of the massive gravitational influence of Jupiter,

Wikipedia summarises this as:

"An early hypothesis, which has since fallen into disfavor, was that the asteroids in the asteroid belt are the remnants of a destroyed planet. (The name Phaeton was suggested for this hypothetical object by the Russian Yevgeny L. Krinov.)

There are two key problems with this hypothesis. One is the large amount of energy which would be required to achieve this kind of effect. The other is the low combined mass of the current asteroid belt, which has 4% of the mass of Earth's moon."

HOW DID PLANETS FORM?

Rather, the currently accepted theory of planetary formation is the nebular hypothesis. During the first few million years of the solar system's history, planets formed by the accretion of smaller planetesimals. Low energy collisions allowed these planetismals to adhere to each other through mutual gravitational attraction. Repeated collisions led to the familiar rocky planets and to the gas giants.

From this point of view, the asteroid belt was a failure to complete the process of planetary formation: it never really got fully into its stride.

What are planetesimals? They are solid objects thought to exist in protoplanetary disks and in debris disks.

A widely accepted theory of planet formation, the so-called planetesimal hypothesis of Viktor Safronov, states that planets form out of dust grains that collide and stick to form larger and larger bodies. When the bodies reach sizes of approximately one kilometer, then they can attract each other directly through their mutual gravity, aiding further growth into moon-sized protoplanets enormously.

This is how planetesimals are often defined. Bodies that are smaller than planetesimals must rely on brownian motion or turbulent motions in the gas to cause the collisions that can lead to sticking.

Alternatively, planetesimals can form in a very dense layer of dust grains that undergoes a collective gravitational instability in the mid-plane of a protoplanetary disk.

Many planetesimals may eventually break apart during violent collisions, but a few of the largest planetesimals can survive such encounters and continue to grow into protoplanets and later planets.

In regions where the average velocity of the collisions is too high, the shattering of planetesimals tends to dominate over accretion, preventing the formation of planet-sized bodies. The region lying between the orbits of Mars and Jupiter contains many strong orbital resonances with Jupiter.

As Jupiter migrated inward following its formation, these mean motion resonances would have swept across the asteroid belt, dynamically exciting the region's planetismal population in the process.

Planetesimals in this region were (and continue to be) too strongly perturbed to form a planet. Instead the planetesimals continue to orbit the Sun as before, and the asteroid belt can be considered a relic of the primitive Solar System.

Answer 2

You could call the asteroids part of a planet that never formed but they are unlikely to have been a planet that was somehow destroyed. Also if you clumped all the asteroids toghether it would form a world smaller than Mercury.
It is rare these days but earlier in the solarsystems youth collisions between asteroids were much more common. You just have to look at the moon to see proof of impacts. Every crater means an impact that increased the moons mass by a tiny amount. Earths mass increases by several tonnes each year. Right now there is the Lyrid meteorshower that will incease earths mass by several pounds.
But the asteroidbelt probably is what it is because gravitational resonance from Jupiter keeps all that debris from forming a whole world. This resonance causes gaps in the asteroidbelt. These gaps are also called the Kirkwood gaps and means that Jupiter has "positioned" the asteroids in certain distances from each other in bands. Therefore all those bits of rock never got close enough to become one big world.

Answer 3

There is no definitive evidence that this is the source of the Asteroid Belt. The circumstanial evidence is based on the presence of Jupiter just outside the belt, and the fact that the large asteroids stay between Jupiter and Mars in elliptical orbits like other planets.

It could be possible that prior to the firm establishment of the current solar system, that a different configuration of planets existed, and that
a planet-killer asteriod or something like that smashed into a Mars-like planet and tore it apart. We can guess the impact of not-so-large asteroids on the earth, and the impact on a smaller planet could be more severe.

Answer 4

Apparently there is not enough matter in the asteroid belt to coalesce into a planet. It is likely that it is matter which has been around since the formation of the solar system, was caught in orbit around the Sun, and just never formed into a planet. The total mass of the asteroid belt is about 1/1000th the size of Earth, much smaller than even the Moon. There really is not a lot of material, in astronomical terms.

Answer 5

It could be... my problem with the whole 'lack of mass't theory is that theres been several billion years for asteroids to have been plucked out by Jupiters gravity, or just leave on their own. Maybe there was a planet that was torn apart by Jupiter, then forming it's rings, and possibly some moons. The possibilites are endless, and we just don't know right now.

Answer 6

No one really knows... it could be Leftover from planet building, or it could be a destroyed planet. Theres a dwarf planet in the asteriod belt called ceres so maybe the asteroid belt could be a part of ceres; or Maybe its leftover from planet building because some asteroids have compositions similar to the iner planets

Answer 7

It would be possibility I wouldn't rule out. But on the other hand what if just left overs as the planets were forming too or how about just a bunch of rock that may have came from else were?

Answer 8

Right now, that's the main hypothesis. And we may know more soon--the "Dawn" mission--the first unmanned probes to asteroids (1 to Ceres, 1 to Vesta) are now in transit. That's one of the questions that scientists hope to answer.

Answer 9

Theories are theories are theories. They are no more and no
less. So it really doesn't matter is currently in favor.

Forget about Wika-what ever it's called. You never know who
has made changes to entries.

Answer 10

I agree with Bruce. It was Jupiter's fault.