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Posted on 03/03/2009 7:31:32 PM PST by SunkenCiv
University of Arizona scientists have uncovered a curious case of missing asteroids. The main asteroid belt is a zone containing millions of rocky objects between the orbits of Mars and Jupiter. The scientists find that there ought to be more asteroids there than researchers observe. The missing asteroids may be evidence of an event that took place about 4 billion years ago, when the solar system's giant planets migrated to their present locations. UA planetary sciences graduate student David A. Minton and UA planetary sciences professor Renu Malhotra say missing asteroids is an important piece of evidence to support an idea that the early solar system underwent a violent episode of giant planet migration that might possibly be responsible for a heavy asteroidal bombardment of the inner planets. The scientists are reporting on their research in an article, "A record of planet migration in the Main Asteroid Belt," in the Feb. 26 issue of Nature.
(Excerpt) Read more at sse.jpl.nasa.gov ...
Did 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.
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Is it true that Uranus always gets hit by asteroids from behind?
Seriously, why is it that we never see any big asteroid collision with the moon?
The moon is about 1/4 the size of the earth so I suspect the chances of impact would be about 1/4 less than the chances of a bigun hitting us.
Speaking of missing asteroids, there was a curious, short segment on the news this evening. Apparently, an asteroid described as being as large as a ten story building passed within 45,000 of Earth last month, without detection before the fact. Impact from such an object, had it occurred, was described as being equivalent to 1,000 Hiroshimas.
45,000 miles, sorry.
That would have made for one really bad day.
Because someone has removed them from the Galactic Library?
The only way to handle the missing asteroid problem is to immediately adopt socialism on all planets. If this doesn’t work, more extreme measures may be required.
Little game of intra-solar-system pool with Nibiru as the 8-ball?
These stories are always interesting because lots of people assume that scientists know everything and there is nothing new to learn, but there is still so much that we don’t know. It’s humbling and exciting at the same time. There is always more to learn.
I don't think the size difference is what matters. I would guess that when you take into account the vast distances in the cosmos and the solar system, it is probably the same chance.
I might say that if you played a lottery with a billion to one odds, buying four tickets would not increase your winning potential four-fold.
Yes it would. Learn some math.
Buying four tickets would leave 999,996 losing tickets. Perhaps I explained it incorrectly. The point I'm trying to make is that to have a one in four chance of winning you would have to buy 250,000 tickets.
4everfree2001 has only taught me that he/ she is in a bad mood this evening.
that is true but the moon has a past history of getting lit up by asteroids as is evident on it’s dark side.
At the risk of being labelled hostile, lol, you need to add three more zeroes to your numbers.
Whoops! I wouldn’t label you hostile. His tone was much different. “Learn some math”.
Time to hit the sack...later.
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