That evidence would also support the capture theory. Moreover, all iron on Earth and no iron on the Moon makes for a pretty bizarre collision theory. Capture makes more sense.
Posted on 03/25/2002 2:42:10 PM PST by vannrox
Asteroid Vesta: The 10th Planet? Discovery Brightens Odds of Finding Another Pluto Nemesis: The Million Dollar Question HOUSTON, TEXAS -- Our solar system may have had a fifth terrestrial planet, one that was swallowed up by the Sun. But before it was destroyed, the now missing-in-action world made a mess of things. The temporary existence of more than 4 planet-sized bodies in the inner Solar System is consistent with the currently favored model for the formation of the Moon. Work by Chambers and Lissauer also supports the view that our Moon is a leftover of a massive collision between Earth and a Mars-sized body 50 million to 100 million years after the formation of the Solar System. Wendell Mendell, a planetary scientist here at NASA's Johnson Space Center, said the new theory is intriguing. "By thinking that the Solar System was really quite different in a major way with an extra inner planet, we might be able to develop some sort of self-consistent scenario that explains a lot of things. But all this is at the very early stages now," Mendell said. "You're going to have to be very, very specific on what sites you go to collect new samples," Schmitt told SPACE.com. "It may be very difficult to get an answer without using missions to fairly large impact craters that penetrate through the ejecta. Those impacts are sort of a drill hole into the lunar crust," he said.
Space scientists John Chambers and Jack Lissauer of NASA's Ames Research Center hypothesize that along with Mercury, Venus, Earth, and Mars -- the terrestrial, rocky planets -- there was a fifth terrestrial world, likely just outside of Mars's orbit and before the inner asteroid belt.
Moreover, Planet V was a troublemaker.
The computer modeling findings of Chambers and Lissauer were presented during the 33rd Lunar and Planetary Science Conference, held here March 11-15, and sponsored by NASA and the Lunar and Planetary Institute.
It is commonly believed that during the formative years of our solar system, between 3.8 billion and 4 billion years ago, the Moon and Earth took a pounding from space debris. However, there is an on-going debate as to whether or not the bruising impacts tailed off 3.8 billion year ago or if there was a sudden increase - a "spike" -- in the impact rate around 3.9 billion years ago, with quiet periods before and afterwards?
This epoch of time is tagged as the "lunar cataclysm" - also a wakeup call on the cosmological clock when the first evidence of life is believed to have appeared on Earth.
The great cover-up
Having a swarm of objects clobbering the Moon in a narrow point of time would have resurfaced most of our celestial next door neighbor, covering up its early history. Being that the Moon is so small, Earth would have been on the receiving end of any destructive deluge too.
Moon-walking astronauts brought back a cache of lunar material. Later analysis showed that virtually all impact rocks in the "Apollo collection" sported nearly the same age, 3.9 billion years, and none were older. But some scientists claim that these samples were "biased", as they came from a small area of the Moon, and are the result of a localized pummeling, not some lunar big bang.
There is a problem in having a "spike" in the lunar cratering rate.
That scenario is tough to devise. Things should have been settling down, according to solar system creation experts. Having chunks of stuff come zipping along some hundreds of millions of years later out of nowhere and create a lunar late heavy bombardment is a puzzler.
If real, what were these bodies, and where were they before they scuffed up the Moon big time? The answer, according to Chambers and Lissauer, might be tied to the the Planet V hypothesis.
"The extra planet formed on a low-eccentricity orbit that was long-lived, but unstable," Chambers reported. About 3.9 billion years ago, Planet V was perturbed by gravitational interactions with the other inner planets. It was tossed onto a highly eccentric orbit that crossed the inner asteroid belt, a reservoir of material much larger than it is today.
Planet V's close encounters with the inner belt of asteroids stirred up a large fraction of those bodies, scattering them about. The perturbed asteroids evolved into Mars crossing orbits, and temporarily enhanced the population of bodies on Earth-crossing orbits, and also increased the lunar impact rate.
After doing its destabilizing deeds, Planet V was lost too, most likely spinning into the Sun, the NASA team reported.
Striking view
"This idea and others within the last few years show that the Solar System is filled with all sorts of gravitational resonances...that a lot of potential orbits in the Solar System are chaotic and unstable," Mendell told SPACE.com. "My sense is that this is a new idea. It's another thing to throw into the pot that's not totally crazy."
The work suggests there's a match up in timing, Mendell said, with asteroids striking the Moon and causing the effects that are seen in the dating of Apollo lunar rocks.
"We're moving into a really new regime," Mendell added, "where the Solar System is not a static dynamic place from day one to now. It really might have had some nuances and synchronicities associated with it that we have not really tried to exploit before."
It takes a drill hole Setting the early Solar System and lunar history record straight means going back to the Moon.
"The Moon is still the keystone to our understanding of the Solar System," NASA's Mendell said.
That too is the view of Apollo 17 astronaut, Harrison "Jack" Schmitt. Getting back to the Moon to sort out the real story is a must, he said.
Dating service
Places on the Moon where older, large basins have deposited ejecta are ideal research zones, Schmitt said. Digging into such sites could yield impact glass formed by basins perhaps dating older than 3.9 billion years old, he said.
Just taking spot samples -- say from the Moon's South Pole Aitken basin -- could be risky, in terms of uncovering the Moon's rocky history, Schmitt said. Such a huge area would take multiple robotic or human exploration missions, each with significant roving abilities.
Also known as the "Big Backside Basin," Aitken is the largest impact crater on the Moon, and one of the biggest in the Solar System.
For the near term, sets of low-cost, mini-robotic landers carrying specialized gear would be ideal in opening up the Moon to further exploration, Schmitt said.
"Numbers of targeted missions could get a lot of great information on some of these fundamental questions that we still haven't been able to answer," Schmitt said.
Getting back to the Moon with a settlement for resource exploitation is another step forward. From such a site, human explorers can survey various lunar locales - even the Moon's side that we Earthlings never see, Schmitt said. "Then we can do the kind of thing that Apollo did for the near side of the Moon," he said.
So when are they going to teach his in public school?
Yeah, I wonder if Khan would have been in a better mood had that not happened?
bump
Good post, and thank you for the other one earlier.
>> Such a huge area would take multiple robotic or human exploration missions, each with significant roving abilities.
We have a rover still up there that was hopefully garaged when we left it.
The next manned mission will need to include a can of gas and some jumper cables.
Flapdoodle!
Sagan's theory would require that Venus' atmosphere be in thermal balance, i.e. since all the heat would be derived from the sun, heat taken in and given out should equal eachother.
More flapdoodle.
http://history.nasa.gov/JPL-93-24/ch3.htm
http://www.planetary.brown.edu/planetary/documents/2875.pdf
Note: I know and have worked with Dr. James Head personally.
I hate that fifth planet. I'm glad it's destroyed.
Nope:
Ok, let us take a look at the Moon. :-)
1) How was it formed, 2) what is it made of, and 3) how far away is it are some of the questions that we can begin to answer.
1) How was the Moon formed?
There were at least five major ideas that were proposed as to the formation of the Moon.
Fission – The Moon split off from the Earth.
Capture – The Moon was captured by the gravity of the Earth.
Condensation – The Moon coalesced out of the same “stuff” the Earth did.
Colliding Planetesimals – Formed from colliding Planetesimals during the early formation of the solar system.
Collision – A body collided with the Earth causing a piece of the Earth’s crust to form the Moon from a resultant ring produced by that collision
The evidence points to the collision theory. First, the Moon does not have an iron core. This pretty much rules out that it coalesced from the same cloud of debris that the Earth did. Second, throughout the solar system, the oxygen isotopes have been found to be different. If the Moon were captured, it too would not match the Earth’s oxygen isotope ratio (which it does). Fourth, by looking at the angular momentum and energy required, the theory that the Moon spun off the Earth after the Earth formed does not hold up.
This leaves us with the Collision theory as the best model we have for the formation of the Moon. The resultant collision caused a ring of debris from the Earths crust to form outside the Roche limit. If it had not, tidal forces would have not allowed for the Moon we see today.
A more in depth discussion of tidal locking since the Moon is tidal locked to the Earth. The reason the Moon keeps one face to the Earth (Its rotation on its axis matches the period of its orbit) is it is tidally locked to the Earth. Here is a more in depth explanation. The total angular momentum of the earth moon system, which is spin angular momentum plus the orbital angular momentum, is constant. (The Sun plays apart also) Friction of the oceans caused by the tides is causing the Earth to slow down a tiny bit each year. This is approximately two milliseconds per century causing the moon to recede by about 3.7 centimeters per year. As the Earth slows down, the Moon must recede to keep the total angular momentum a constant. In other words as the spin angular momentum of the earth decreases, the lunar orbital angular momentum must increase. Here is an interesting side note. The velocity of the moon will slow down as the orbit increases.
The asteroid belt has an estimated total combined mass of less than 1 tenth of the Earth’s moon. Which pretty much rules out that it is an "exploded" planet.
Also Jupiter has a profound effect on the asteroid belt.
Jupiter has a semimajor axis of 5.2 Astronomical Units, thusly its orbital period is 11.86 years. Since the asteroids are not all at the same distance from the sun, some of them will have an orbital period of one half that of Jupiter. This puts those asteroids in a 2:1 orbital resonance with Jupiter. The result of this resonance is gaps called the Kirkwood’s gaps.
So here is the rub, why did not these asteroids form a small planet in the first place?
The reason is the gravitational force of Jupiter. It perturbs the asteroids giving them random velocities relative to each other. Another effect of both Jupiter and the Sun on the asteroid belt is a group of asteroids that both precede and follow Jupiter in its orbit by 60 degrees. These asteroids are known as the Trojans.
Meant to ping you to 108 as well.
What if it's mostly made out of lead?
Then it COULD be a planet.
How about that, smart guy? Huh? Huh? (Pushes you on your shoulder)
Got you fooled I see! :-)
Hmmm... Lead... bet Osmium would even be better. LOL!
I believe the theory you stated about collision.
Although, I believe the moon drifts from earth as it has since it coalesced. The earth has so much gravitational pull to hold items in orbit. After the moon starts to coalesce then this mass would cause more of a pull away from the Earths gravity. This gradual coalescing caused the moon to slowly drift away because the Earth does not increase it's gravity to hold the larger mass at a constant orbit. I also believe this may have happened after the formation of our sun. I would guess that our planets slowly move away from our Sun as our planets slowly gathered more mass. I also believe this to be the reason some moons spin backwards. Many religious people claim this to be their point that there has to be a God because it makes no sense. Clouds of gases can easily start to rotate in an opposite direction as do some hurricanes and tornados.
"I fired all our lumberjacks and hired just one guy to replace them."
"One guy?"
"Yeah! He hails from the Sahara Forest."
"Don't you mean the Sahara Desert?"
"Sure, now..."
When the Days Were Shorter
Alaska Science Forum (Article #742) | November 11, 1985 | Larry Gedney
Posted on 10/04/2004 10:31:59 AM PDT by SunkenCiv
http://www.freerepublic.com/focus/f-chat/1234919/posts
The asteroids seem to have structure, at least the ones we have seen up close. Also, there is differential composition from one asteroid to the next. We might compare this to the situation with Jupiter's moons and Saturn's, where structural and differential composition are pronounced. Could the asteroids, especially the smaller ones, have structure, and could they have differential composition unless they were parts of one or more large bodies that somehow were blasted apart? Whether they were all one at some time past is probably not a requirement, but they might have been parts of several bodies like Jupiter's moons.
That evidence would also support the capture theory. Moreover, all iron on Earth and no iron on the Moon makes for a pretty bizarre collision theory. Capture makes more sense.
We don't have enough evidence to flatly state the above.
For instance, if Oxygen isotope ratios are influenced by distance to the Sun, then a captured Moon might very well eventually match its captor.
Ditto for the hypothetical of oxygen isotope ratios being influenced by comet/asteroid bombardment.
No. The "rub" is that somehow those bodies had enough gravity to form solid rocks from their proposed original cloud of gas...but not enough gravity to form a planet or moon.
In other words, why don't we still see gas out there?!
No, little rocks are more likely remnants of larger rocks (kaboom). Either gas builds and builds into greater and greater solids as a body's gravity increases or not.
Been there, read that long ago ...
The Earth Without the Moon (snip)
The period when the Earth was Moonless is probably the most remote recollection of mankind. Democritus and Anaxagoras taught that there was a time when the Earth was without the Moon.(1) Aristotle wrote that Arcadia in Greece, before being inhabited by the Hellenes, had a population of Pelasgians, and that these aborigines occupied the land already before there was a moon in the sky above the Earth; for this reason they were called Proselenes.(2)
Apollonius of Rhodes mentioned the time “when not all the orbs were yet in the heavens, before the Danai and Deukalion races came into existence, and only the Arcadians lived, of whom it is said that they dwelt on mountains and fed on acorns, before there was a moon.” (3)
Plutarch wrote in The Roman Questions: “There were Arcadians of Evander’s following, the so-called pre-Lunar people.”(4) Similarly wrote Ovid: “The Arcadians are said to have possessed their land before the birth of Jove, and the folk is older than the Moon.” (5) Hippolytus refers to a legend that “Arcadia brought forth Pelasgus, of greater antiquity than the moon.”(6) Lucian in his Astrology says that “the Arcadians affirm in their folly that they are older than the moon.”(7)
Censorinus also alludes to the time in the past when there was no moon in the sky.(8)
Some allusions to the time before there was a Moon may be found also in the Scriptures. In Job 25:5 the grandeur of the Lord who “Makes peace in the heights” is praised and the time is mentioned “before [there was] a moon and it did not shine.” Also in Psalm 72:5 it is said: “Thou wast feared since [the time of] the sun and before [the time of] the moon, a generation of generations.” A “generation of generations” means a very long time. Of course, it is of no use to counter this psalm with the myth of the first chapter of Genesis, a tale brought down from exotic and later sources.
The memory of a world without a moon lives in oral tradition among the Indians. The Indians of the Bogota highlands in the eastern Cordilleras of Colombia relate some of their tribal reminiscences to the time before there was a moon. “In the earliest times, when the moon was not yet in the heavens,” say the tribesmen of Chibchas..."
http://www.varchive.org/itb/sansmoon.htm
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