Posted on 08/24/2007 1:21:38 PM PDT by blam
Jupiter increases risk of comet strike on Earth
11:53 24 August 2007
NewScientist.com news service
David Shiga
Earth experienced an especially heavy bombardment of asteroids and comets early in the solar system's history (Illustration: Julian Baum)
Contrary to prevailing wisdom, Jupiter does not protect Earth from comet strikes. In fact, Earth would suffer fewer impacts without the influence of Jupiter's gravity, a new study says. It could have implications for determining which solar systems are most hospitable to life.
A 1994 study showed that replacing Jupiter with a much smaller planet like Uranus or Neptune would lead to 1000 times as many long-period comets hitting Earth. This led to speculation that complex life would have a hard time developing in solar systems without a Jupiter-like planet because of more intense bombardment by comets.
But a new study by Jonathan Horner and Barrie Jones of Open University in Milton Keynes, UK, shows that if there were no planet at all in Jupiter's orbit, Earth would actually be safer from impacts.
The contradictory results arise because Jupiter affects comets in two different, competing ways. Its gravity helps pull comets into the inner solar system, where they have a chance of hitting Earth, but can also clear away Earth-threatening comets by ejecting them from the solar system altogether, via a gravitational slingshot effect.
Tripled impacts
According to the new study, the worst scenario for Earth is when Jupiter is replaced by a planet with about the mass of Saturn. "[Such a planet] is fairly capable of putting things into an Earth-crossing orbit, but still has some difficulty ejecting them, so they will stay on an Earth-crossing orbit for a much longer time," Horner told New Scientist. The projected result was more than three times as
(Excerpt) Read more at space.newscientist.com ...
You “missed” the point: without planets, there’s nothing to impact!
Well nobody better touch Io! I already built the Walmart and the McDonalds is scheduled to open next week. If you want to come check it out you can stay at the Motel 6. I’ll even leave the light on for you.
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44 New Satellite orbits...new! What's going on 'up' there?
Jupiter, the Solar System vacuum cleaner?
As distance is more important than mass, stuff passing by Jupiter will experience trajectory changes. However, the mass of Jupiter is a pretty small fraction of the mass of the Sun, and Jupiter is only on one side at a time, so IMHO, Jupiter doesn’t do much to attract bodies into the Solar System. However, Jupiter will eject some stuff, shepherd other stuff, capture some other stuff (such as those dozens of retrograde moons, to say the least), and absorb still other stuff (SL-9). Shepherded material (such as the asteroid belt) won’t remain forever where it is, as Jupiter continues to mess with it. :’)
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'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.Jupiter 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 1999Newfound Moons Tell Secrets of Solar SystemThe fact that most of the satellites' orbits are retrograde and eccentric speaks volumes about their origins: They had to have come from elsewhere, and been captured by the planets at some point. If they formed at the same time as the planets, from the spinning nebular disk, their orbits would be nearly circular and in the same direction as the planets' rotation, like the "regular" moons... In the case of the irregular satellites, they could not have shifted from an orbit around the Sun to an orbit around one of the giant planets without slowing down -- through friction in an atmosphere, perhaps; the influence of gravity; or a collision with another object... But there are two other possibilities for capture, Dr. Nesvorny said. One is that rapid growth of the core led to a corresponding increase in gravity, enough to pull down a nearby object. The other is that captured objects were a result of a collision between two planetesimals, the force of the collision being enough to dissipate the energy of at least one of them. Either of these two theories may be a more likely explanation for the satellites of Uranus and Neptune, which formed differently from Jupiter and Saturn, without the large amounts of gas.
by Henry Fountain
August 12, 2003How Jupiter Got BigThe traditional view is that Jupiter first formed a rocky core, several times the size of Earth, which then attracted a still larger outer envelope of gas. This process is known as "accretion." But there are problems with this model. The major problem is that if the large, gaseous planet did form by the gradual accretion of material, it would have taken a very long time to develop. Current estimates range between 10 million and 1 billion years. However, recent observations of distant stars suggest that planets have at most a few million years or less to gather up as much dust and gas as they can before the protoplanetary disk that feeds them disappears.
by Leslie Mullen
June 2, 2002)
The Original Solar System...this scenario implies that Jupiter's mass has been increased from its original value by some unknown but significant amount. This apparent fact makes us pause to consider whether we must regard Jupiter as a contradiction of the fission theory simply because its mass is larger than Saturn's. Perhaps its original mass was smaller than Saturn's. Among the supporting evidence for this conjecture we find suggestions that Jupiter's mass has apparently increased by roughly 40% just since its asteroidal moons were captured, probably within the last billion years. [188 Byl, J. and Ovenden, M.W., "On the satellite capture problem," Mon.Not.Roy.Astron.Soc. 173, 579-584 (1975).]
by Tom Van Flandern
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http://www.ifa.hawaii.edu/~sheppard/sheppardjupiter.pdf
http://www.ifa.hawaii.edu/~sheppard/satellites/
http://i10.tinypic.com/63v69lg.jpg
I was waiting to reply to that to see if someone else would have the same thought.
thanks, more homework...
I'm glad somebody has a reasonable suggestion.
Jupiter, from "Jove Pitar" = "God, the Father". There are no coincidences. "Carl Rove" = "Rove, da Man!"
The accepted theory is that without Jupiter, the asteroid belt would indeed "collapse" or coalesce into a planet. A planet didn't form at that location because of tidal distruptions from Jupiter. In the messy process of coalescence some chunks would be heaved into highly elliptical earth crossing orbits. It certainly happened in the early days of the solar system, the moon retains the scars. In fact, the moon arose as a result of impact between proto-earth and another proto planet.
In the early days of the solar system, there were numerous collisions, but most the formation debris has been cleaned up, mostly by Jove, the Father. Earth crossers are the anomaly these days.
Not as soon as John Evander Couey will.
Don't be so sure. I'm 56 and may well not live to see him die.
The message just popped up on my monitor after this really big black thing landed in my backyard!?!?!?!?
Don’t touch it. Or, alternatively, take it to Africa and bury it. Or launch it to the Moon, somewhere near Tycho crater. But if it starts breaking off into chunks you might want to burn it, I hear those things get nasty once they start replicating.
This is an old theory and is no longer accepted. The old theory said that there was a fifth planet that Jupiter shattered. This is not accepted today. The best explanation is that during the formation of the Solar System when planets were forming, there were some objects that had too high of relative velocities to ever be captured. Eventually with the formation of Jupiter there became a band between orbital resonances where objects were captured. As Jupiter migrated inwards this band was compressed. Over time the vast majority of the mass of the asteroid belt has been ejected so that it now has maybe 0.1% of the mass of the Earth.
Maybe this will be an exception. Remember Jefferey Dahmer and the pedophile priest Gagin(sp)? If ths scumbag is released in General Population, the boys inside will take care of the problem. And if that happens, perhaps the legal system will go easy on the one or ones that did it.
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