Posted on 01/14/2010 3:15:11 PM PST by SunkenCiv
Beyond Neptune lies a reservoir of... icy debris left to roam the solar system's dim outer limits having never coalesced into planets... Named for astronomer Gerard Kuiper, who in 1951 predicted the existence of this 3-billion-kilometer-wide swath of icy chunks, the Kuiper belt didn't begin to reveal itself to observers until 1992. Since then, researchers have found more than a thousand bodies filling a doughnut-shaped belt, which extends 30 to about 50 astronomical units from the sun. One astronomical unit is the average distance between the Earth and sun... The puffed-up, elongated orbits and present-day sparseness of the belt all but scream that the region had a close and violent encounter with at least one of the outer planets, says theorist Hal Levison of the Southwest Research Institute in Boulder, Colo. Recent findings are providing new evidence of this long-ago melee, and the details could help scientists reconstruct early conditions in the solar system... the belt's biggest bodies, such as Pluto and Eris (the largest known in the region), would never have formed unless they originally followed more circular, low-inclination orbits. In addition, the belt must have been much more crowded and thousands of times heavier than it is today... Such changes are a smoking gun that an intruder must have plowed into the Kuiper belt, he says. Whatever disturbed the belt also removed 99.99 percent of its mass. The obvious suspect is Neptune, the closest large body to the belt, says observer Mike Brown of Caltech... In one scenario, suggested earlier in the decade by Levison and his colleagues, Neptune and its three larger compatriots -- Jupiter, Saturn and Uranus -- were once packed together into a region only about half the diameter of Neptune's current orbit...
(Excerpt) Read more at sciencenews.org ...
Today's Kuiper belt orbits View larger version | The elongated, highly inclined orbits of many of the denizens in the doughnut-shaped Kuiper belt (shown in blue) suggest that a massive intruder barged into the belt early in the history of the solar system, ejecting bodies and jumbling orbits.Illustration by Anil Rao
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...In one scenario, suggested earlier in the decade by Levison and his colleagues, Neptune and its three larger compatriots -- Jupiter, Saturn and Uranus -- were once packed together into a region only about half the diameter of Neptune's current orbit...
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"When a thing is new, people say: 'It is not true.' Later, when its truth becomes obvious, they say: 'It is not important.' Finally, when its importance cannot be denied, they say: 'Anyway, it is not new.'" -- William James, 1896
"Theories have four stages of acceptance: i) this is worthless nonsense; ii) this is an interesting, but perverse, point of view; iii) this is true, but quite unimportant; iv) I always said so. -- J.B.S. Haldane, 1963
same author, was referenced in the article:
http://sciencenews.org/view/feature/id/40390/title/The_Solar_Systems_Big_Bang
Gas giants credited for solar system formationJupiter and Saturn form the basis of a "grand unified theory" of the solar system, according to new computer simulations. The research traces three seemingly unrelated phenomena - the giant planets' orbits, craters on the Moon, and the behaviour of certain asteroids - to the motions of the two gas giants nearly four billion years ago... an international team of researchers has performed computer simulations that reproduce the orbits of the four giant planets - Jupiter, Saturn, Uranus, and Neptune - in exquisite detail. The team has published a trio of papers about their findings in Nature. In the model, the four planets form in 10 million years within the current orbit of Uranus. Surrounding them in a ring are several thousand rocky objects called planetesimals, left over from the formation of the planets... planetesimals begin to "leak" into the giant planet zone and the orbits of the giant planets gradually change. After 700 million years, Saturn has migrated outward and Jupiter inward to the extent that they reach a "resonance" point. This means they begin to march in lockstep with each other, with Jupiter completing two orbits around the Sun for every one of Saturn's. The resonance allows the pair to greatly disturb the orbits of the other planets.
by Maggie McKee
25 May 2005Did Jupiter Bully Other Planets in Sibling Rivalry?One possible explanation, discussed in Thursday's issue of the journal Nature, is that Uranus and Neptune formed much closer to the center of the action than their current positions might indicate. In this scheme, Jupiter and Saturn were bullies of a protoplanetary playground, shoving the other two future giants out of the way.
by Robert Roy Britt
8 December 1999Jupiter gave birth to Uranus and NeptuneNot too long ago, scientists regarded the orbits that the planets circle our Sun as being the ones they were born in. Now they are realising that this is not the case. Uranus and Neptune may have migrated outwards and Jupiter may have come in from the outer cold. Scientists have always been slightly puzzled by the positions of Uranus and Neptune because in their present locations it would have taken longer than the age of the Solar System for them to form. Scientists from Queen's University suggest that the four giant planets started out as rocky cores in the Jupiter-Saturn region, and that the cores of Uranus and Neptune were tossed out by Jupiter's and Saturn's gravity.
by Dr David Whitehouse
8 December, 1999Jupiter's Composition Throws Planet-formation Theories into DisarrayExamining four-year-old data, researchers have found significantly elevated levels of argon, krypton and xenon in Jupiter's atmosphere that may force a rethinking of theories about how the planet, and possibly the entire solar system, formed. Prevailing theories of planetary formation hold that the sun gathered itself together in the center of a pancake-shaped disk of gas and dust, then the planets begin to take shape by cleaning up the leftovers. In Jupiter's current orbit, 5 astronomical units from the sun, temperatures are too warm for the planetesimals to have trapped the noble gases. Only in the Kuiper belt -- a frigid region of the solar system more than 40 AU from the sun -- could planetesimals have trapped argon, krypton and xenon.
by Robert Roy Britt
Nov 17 1999
While lead researcher Tobias Owen does not put much stock in the idea that Jupiter might have migrated inward to its present position, other scientists on the team say the idea merits consideration. Owen expects the probes will find similarly high levels of noble gases in Saturn, Uranus and Neptune. Hints of these gases have even been found in the thick atmosphere of Venus, another planet now begging more study.
Don’t suppose Neptune could have steadied the orbits of the objects nearest the center?
Neptune has a disrupted moon system, but its axis is basically perpendicular to the ecliptic; closer-in but less massive Uranus has a tipped axis but a basically normal moon system. One might say that Neptune absorbed the “missing” KBOs — or one could simply say, the standard model for planetary system formation is wrong. :’)
And further out is the Oort cloud...extending 3 light years. Mighty big.
Interesting, since the nearest neighboring star is Proxima Centauri, about 4.2 LY away. So basically, matter from our solar system is bumping into matter from next door.
It's like the electron clouds in two atoms brushing each other, but the nucleus is way down at an almost infinitely removed ratio from the atom's "surface"; much like the planets in a solar system.
Your William James quote came in handy on a CPAC thread.
Thanks!
My pleasure. :’)
The Oort Cloud has never been seen, not even a little bit; so far it exists only as a kludge to account for blackboard problems with the conventional model(s) for planetary system formation. :’)
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