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BillFerris
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Reged: 07/17/04

Loc: Flagstaff, Arizona, USA
Re: Is Bode’s Law Universal? new [Re: llanitedave]
      #5601592 - 01/02/13 05:04 PM

If Earth has migrated from a different orbit to its current distance from the Sun, then the Moon tagged along for the ride. One could approach the question from a standpoint of what one would expect to find at or near the lunar surface. For example, should older lunar impact craters exhibit certain characteristics if they were made by asteroids typically orbiting at different distances from the Sun?

Another approach could be to compare a model of Earth's structure--especially the core--with models of the solar nebula and the distribution of heavy elements during the time of planetary formation. If Earth had formed elsewhere, should its iron core be smaller or larger? Differently composed?

Finally, If the Earth were in a different orbit 1 to 2 billion years ago, shouldn't the geological record retain some evidence of climatic evolution tied to a move from the former to the current location? There are places on Earth where one can gain relatively easy access to rock layers that were formed 1 to 2 billion years ago. Let's have a look.

As to the question of whether or not Earth migrated to its current orbit from another, I look at the two options--formed here and survived because it's a stable orbit versus formed in an unstable orbit and was lucky enough to move to a stable orbit--and I lean in favor of the former. In the absence of persuasive evidence to the contrary, it seems more likely that a planet will remain in the stable orbit in which it formed versus moving from an unstable to a stable location.

Bill in Flag


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Rick Woods
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Reged: 01/27/05

Loc: Inner Solar System
Re: Is Bode’s Law Universal? new [Re: BillFerris]
      #5601634 - 01/02/13 05:30 PM

Tsk! Hasn't anyone read Velikovsky?

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llanitedave
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Reged: 09/26/05

Loc: Amargosa Valley, NV, USA
Re: Is Bode’s Law Universal? new [Re: Rick Woods]
      #5602102 - 01/02/13 10:52 PM

In all fairness to Velikovsky, it was he who first got me interested in science.

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llanitedave
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Reged: 09/26/05

Loc: Amargosa Valley, NV, USA
Re: Is Bode’s Law Universal? new [Re: BillFerris]
      #5602125 - 01/02/13 11:06 PM

Quote:

If Earth has migrated from a different orbit to its current distance from the Sun, then the Moon tagged along for the ride. One could approach the question from a standpoint of what one would expect to find at or near the lunar surface. For example, should older lunar impact craters exhibit certain characteristics if they were made by asteroids typically orbiting at different distances from the Sun?

Another approach could be to compare a model of Earth's structure--especially the core--with models of the solar nebula and the distribution of heavy elements during the time of planetary formation. If Earth had formed elsewhere, should its iron core be smaller or larger? Differently composed?

Finally, If the Earth were in a different orbit 1 to 2 billion years ago, shouldn't the geological record retain some evidence of climatic evolution tied to a move from the former to the current location? There are places on Earth where one can gain relatively easy access to rock layers that were formed 1 to 2 billion years ago. Let's have a look.

As to the question of whether or not Earth migrated to its current orbit from another, I look at the two options--formed here and survived because it's a stable orbit versus formed in an unstable orbit and was lucky enough to move to a stable orbit--and I lean in favor of the former. In the absence of persuasive evidence to the contrary, it seems more likely that a planet will remain in the stable orbit in which it formed versus moving from an unstable to a stable location.

Bill in Flag




We're looking back way further than 1-2 billion years. We're looking for things happening associated with the Late Heavy Bombardment some 3.9 billion years ago, in response to the hypothesized dynamic migration of the orbits of the outer planets. Climatic evolution would be obscured by a combination of the evolution of life and photosynthesis, the steady increase in the solar output, the bombardment itself, and the changing nature of the crust and the oceans as plate tectonics developed.

We have a very dynamic history to deal with, and much of its effects are un-postdictable.

As for the stability of past orbits, that again is hard to establish -- in fact, it's even hard to agree on what we mean by "stable". It's obvious that the original orbits of Jupiter and Saturn were unstable, as they influenced each other and were influenced in turn by the billions of bodies sharing their zones. If the Earth's original orbit was stable, the question is whether it would have become unstable due to the increasing perturbations of Jupiter's influence as the latter migrated ever closer to the Sun. That's my real question. And if the Earth's orbit was influenced, that of Mars would have been affected even more.

Since the formation of the Solar System was such a chaotic process, I hesitate to claim that any planetary orbit was stable until all the debris was cleared out and the different resonances settled down.


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Rick Woods
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Reged: 01/27/05

Loc: Inner Solar System
Re: Is Bode’s Law Universal? new [Re: llanitedave]
      #5602251 - 01/03/13 12:59 AM

Quote:

We have a very dynamic history to deal with, and much of its effects are un-postdictable.





Un-postdictable! Ooo, I like that!


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Brian Albin
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Reged: 08/22/06

Loc: Western Oregon
Re: Is Bode’s Law Universal? new [Re: Rick Woods]
      #5602302 - 01/03/13 02:18 AM

I don’t want to interrupt this flow of ideas (at least not now that those damned puns have stopped), But I wanted to say hello and let everyone know I have read what has been posted and thank you for it. It is good to have a place to share an idea and get it thought over by those who know more about it than I.

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Dave Mitsky
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Reged: 04/08/02

Loc: PA, USA, Planet Earth
Re: Is Bode’s Law Universal? new [Re: Brian Albin]
      #5603003 - 01/03/13 01:27 PM

There's an article on a new model of Jupiter's rolling-stone past at http://www.nasa.gov/topics/solarsystem/features/young-jupiter.html

Dave Mitsky


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