frankglennjacobs@gmail.com

Thank you.

What got me off on this speculation was the news that any number (dozens? hundreds?) of "Hot Jupiters" had been found. (I suppose the really short-orbit giant planets have the easiest signtures to read.)

That is why I asked if those planets had been formed close to their stars, where we find them now -- or formed way up and migrated down.

That leads us to our own Solar System, with no "Hot Jupiter". No indication that Jupiter ever traveled thru the inner Solar System.

That's why I asked if some previous giant planet had ever migrated thru down here, wrecked whatever existed at the time, and then been absorbed by the sun. (And became "The Late Great Hot Jupiter"?)

Some of the asteroids are shaped like potatoes. At least one of them appears to be solid metal. That indicated to my unscientific mind that they were poured out hot and rotating, and not formed by little "asteritos" banging into each other..

Jupiter migrated. So it was not always where it is now. Speculate unto your self that a planet was once where the Asteroid Belt is, and, when Jupiter migrated to its present station, that planet (and maybe several others?) was disrupted. Speculate that 98% of the blobs fell into Jupiter, some were entirely ejected from the Solar System and some remained in that approximate orbit, rotating into potato shaped asteroids as they cooled.

Again, this is not a theory. It is not a hypotheses. It is not a position nor a proposal. It is only a notion, a SWEG, reinforced in my dark, unscientific mind by the neat photographs of some of the potato-shaped asteroids.

- - - - - -

It was the fairly recent collision of a comet with Jupiter that got me going on the "captured asteroid" idea. But there was never a chance of it being captured. It broke up when it got to it's own Roche Limit, did one most-eccentric orbit and impacted plop plop plop plop.

Every close encounter of two bodies has five possibilities.

PLAN A: Straight-on impact.

PLAN B: A clean miss with a resultant perturbed orbit.

PLAN C: Great loss of energy in atmospheric friction could result in an orbit of sorts. However, at the end of the first orbit is impact. Plop!

PLAN D: When one body breaks up and everything is "just right" and part of one body is ejected in one of those famous "just right" space-shuttle slingshot maneuvers, and the energy gained by the ejected part is lost by another part and just happens to be "just right", part goes into orbit and stays there.

PLAN E: The approaching body is drawn into the atmosphere of the other, and just happens to lose "just right" amount of energy to go into orbit.

I don't know of any other hypothetical case in which a solid body can be "captured". As you said, very difficult and improbable.

I imagine, therefore, that successful captures tend to be very messy, with fractal physics making lots and lots of little pieces for each big piece.

I am not the judge of your explanations.

I appreciate the effort you have made in explaning.

I went and read some about ice giants and gas giants. Yes, they are quite different.

I believe I understand your commentary on collisions.

Almost every single case of Roche Limit disruption leads within hours to a head-on lithosphere-to-lithosphere collision. About a generation ago, we got to WATCH just such a collision between a comet and Jupiter.

Without doing the math, it seems to me that all the planets, planetoids and planetesimals in the inner Solar System were destroyed in just such train-wrecks, with the manifest exceptions of Earth and Mars. (And if the Asteroids were ever part of a planet, about 99% of that one fell into Jupiter, too.) You have added Venus and Mercury to that list -- perturbed but not destroyed.

Technical question: Is the current thinking that the giant planets migrate down toward the sun as long as there is enough trash in the orbital plane to slow them down?

Technical question: Are the remaining giant planets still up there because their predecessors cleared the orbital space?

Technical question: Do the Exo Hot Jupiters migrate right on down into their stars?

Technical question: Do those stars keep on bringing forth new giants?

Technical question: Do stars keep on bringing forth new rocky planets?

Technical question: Is Sedna sort of a junior icy planet?

Technical question: Can an asteroid be captured without (1) bringing along a twin to be ejected from the system? -- (2) providing its own sacrificial twin by breaking up on approach?-- or (3) losing lots of energy in the atmosphere. (Each case is, of course, one of those "just-right" circumstances.)

Thank you again, Argent.

Again, I have no theory. I wouldn't know what to DO with a theory -- or even a hypothesis -- since I have no idea about the math.

This is, again, a SWEG -- a mere speculation. It doesn't even rise to the level of a proposal.

And, to show you where I'm coming from, I think maybe I was thrown out of Science Forum for speculating that Niburu had done all that planetary damage. The stuff about a Flat Earth was only jokingly sarcastically thrown in with the material on the aether.

The new idea (well, new to me!) that planetary orbits migrate relieves Niburu of all the blame. Not to even be considered any more!

"Hell-bent" is way overstating my zeal. I never even bothered to find out what kind of math is involved in understanding the issue.

It would appear to me that of the proto-planets disrupted by the gravity of some migrating planet, only three partly survive: Earth, Mars and the un-named planet formerly between Mars and Jupiter. (You have added Mercury, with a "missing mantle" and Venus with the strange rotation.)

Since you have taught me that planets migrated down toward the sun, moved on by the drag of the protoplanetary disk -- and most probably were either destroyed on the way or absorbed into the sun -- that's a lot of collisions. Way more than I ever imagined. Surprise! Surprise!

With that sort of set-up, it is surprising that ANY planets remain in the inner Solar System.

How did Venus keep its vast atmosphere? What sort of encounter could cause it's strange rotation? Or is Venus a sort of Junior Jupiter stranded in place on its way? Or is it still headed down toward the sun?

How'd Jupiter stop where it is? Same way? Run out of dust? Or is it still migrating?

I am trying to understand the "wake" of which you spoke: The tremendous tonnage of stuff surrounding a planet is almost all moving in approximately the same orbit with it. However a passing giant pulls all sorts of gas and dust along behind it -- and in from all sides. This adds up to, perhaps, the mass of a small planet, centered behind. This is continually pulling the giant back and slowing up its progress-in-orbit. Further, the giant's gravity pulls gas and dust to itself as infall. That which hits it anywhere at all (except in back) adds to the mass of the giant, but not to its energy. This is a new idea to me and I am only guessing. Let me guess some more here: Every gravitation pull on anything transfers energy somewhere. This will either go to entropy, heat or movement.

As to results of near collisions, it has been pointed out that I am relying on very rare "just right" Roche-Limit encounters.

But many things in the Universe came about by "just right" encounters. However the moon got there is because something went "just right". I propose that astrophysicists contemplate whether it was as a "just-right" Roche-Limit partial-disruption of Proto-Earth.

Straight technical question: Is the "drag" that causes migrations the gravitational interaction with other planets, meteoroids, dust and gas still in orbit at that time around a star?

Speculative question: Were there likely more planets before the migration? That is, did any get destroyed in collisions?

Straight speculation: Migrating planets, great and small, influenced one another with everything from orbital perturbations to head-on lithosphere-to-lithosphere collisions -- and every sort of inconvenience in between.

Be so kind as to answer. Thank you.

Thank you, um 'Argent'.

I do appreciate the straight answers.

Years back -- as it were, in a former lifetime -- the Science Forum honchos would give me answers something like "What drivel!" and "You know absolutely nothing, because you can't do the math."

This is a most refreshing change.

In my first speculation in this century (which I mistakenly put into a now-locked new thread) I speculated that this new knowledge about migrating planetary orbits removed the temptation to blame all the astro-physical damage on the probably-mythical Niburu.

Seeing that Jupiter (or some other planet) had probably migrated thru the Solar System, that would account for everything from perturbed orbits to altogether missing planets.

Technical question: By "drag" do you mean the accumulated force on a planet caused by all those little space thingies banging into it as it goes along?

Thank you again.

Very neat. "ice giants" v "gas giants". How about that?! And here I thought they were all alike as marbles in a bag!

The discovery of "Hot Jupiter" exoplanets has joggled my imagination into speculation and questions.

Did the rocky planets migrate as well?

Is the Solar System migration over now that most of the small stuff has been swept out of the solar main orbital plane?

Were the exo-hot-Jupiters fromed right down on the deck where we find them?

Were they formed several AU from their stars and migrated down to meet them?

Will they impact their stars?

Did previous such planets in our Solar System impact the Sun?

What effect would such a planet have in migrating its orbit past a rocky planet?

(I speculate what I speculated in my previous speculation, plus that out of a possible thousand rocky planets, only four partly survived the passing-migrating Jupiter treatment.)

P. S. Years back when I was excommunicated from Science Forum, the then-current thinking about the formation of the moon involved a very involved double bump. I am glad you have purged such heretical thinking from your catechism.

P.P.S. Encounters between planets involve anything from an orbital perturbation to a direct hit. There is a lot more space out there than rock. Not every Roche Limit encounter is the opening gun to a lithosphere-to-lithosphere collision, although I suppose most of them are. If Jupiter were to have passed Mars closely enough to take its atmosphere and ocean, how long would it be until they were far enough apart again so that the damage would stop continuing? An hour? Two?

Fair enough! You called my speculation a speculation and said to put it in with the other speculations.

Furthermore (also fair!) you said to re-write it as questions.

(Sort of annoyingly, you added, ". . . if you want to learn some science".)

Here goes BOTH:

In the dawn of time, the orbit of Jupiter (and maybe of some other gas giants) migrated.

Did they therefore likely come close to the Roche limit of other planets?

Would the tidal effect likely sweep up atmospheres and oceans?

Would the tidal effect of even closer encounters jerk big pieces of planetary crust away?

{I therefore verily speculate that such an encounter -- rather than the most-unlikely "double-bump" -- formed up the moon. Nyaah! So THERE!}

First off, this ISN'T a "theory". Theories are high and holy and full of math that I don't understand. This isn't even a "hypothesis".

It is what we called in the Army a S.W.E.G. (Scientific Wild-Eyed Guess).

Lately a lot of Hot Jupiters have been found. That may be because they are the easiest to detect.

Again, this isn't theory. (Theories are for people who know what they're doing. I don't.)

PLAN A: They are near the end of spiraling down into their stars.

PLAN B: They are near the beginning of spiraling up from their stars.

PLAN C: They started there and they aren't going anywhere except around and around.

Our own familiar Jupiter either started where it is -- or started close to the sun and gained altitude over the past bazillion years -- or started higher and is gradually working its way down toward the sun, or, even started high, went down and came back up.

We cannot tell by reasoning from general principles that there was not another gas giant which has by now impacted the sun.

Whether going up or going down, if such a planet were precisely in the same orbital plane with the other planets, they would all impact it, one by one, leaving exactly nothing.

Going up or going down, any thing that got within the Roche Limit of a Jupiter-size planet would not merely be perturbed, it would lose something or other.

Now, here comes a Hot Jupiter somewhat-sort of matching the orbit of the ProtoEarth. First thing to go is the atmosphere. Next go the oceans. As the two approach each other, there go some mountain ranges and then maybe a few Tectonic Plates.

This gets messy. As what is left of ProtoEarth and the Hot Jupiter move past each other, most of that rock (mostly basalt) fall into the gas-giant. Most of what is left is scattered into space -- and one spectacularly large piece of basalt, due to coincidental conservation of energy, doesn't do either, but remains in a random orbit.

Untold millions of tons of rock fall back onto the ProtoEarth, onto the ProtoMoon and into the wrecking-ball of a planet.

And there you have the ProtoMoon, with its similar basalt rock, slowly regulating its orbit.

And there you have the ProtoEarth, battered by big rocks, stripped of atmosphere and ocean.

Hundreds of millions of years later (you just can't rush these things) Mars gets the same treatment, only worse, as it has never recovered.

And there is a worse case. An (un-named) planet beyond the orbit of Mars is completely disrupted by the same tidal forces. Nine tenths of it falls into Jupiter. Nine tenths of what is left is scattered at random into all of space. And the one percent that is left remains in wild random orbits. We call that area The Asteroid Belt.

Nobody can tell if Jupiter is still going up. Nobody can tell if it will catch up to Saturn.

[in case that was not Jupiter coming up, but a Hot-Jupiter going down, just reverse the order of those astronomic shipwrecks.]

[in case Jupiter is not going anyplace, we can always go back to the "Niburu" notion.]