Wandering Jupiter

[JoeSchmuckatelli]

I've lately run into a few shows and articles suggesting that Jupiter migrated orbits way back in the way back.  One suggested it started out about where it is now, then wandered into the inner solar system, and then back out again to its current orbit (along with Saturn).  Another couple have suggested that Jupiter formed way out in the icy distant parts of the solar system, only to later migrate in to the current position.

 

From what I can tell, the purpose of the suppositions is to explain some of the chemical anomalies of the planet itself, while others are based on observational data of hot Jupiters around a bunch of stars...

My question is how?  I'm very hazy on how a planet can migrate orbits - and the articles I've read and the programs have failed to break it down Barney style enough for this old jarhead to figgur out.

 

Appreciate anyone willing to tackle this one!

[Scotius]

Inwards migration is easy to explain: friction from the material in the planetary disc. There was enough dust and gas in proto-Jupiter's path to slow it down, thus shrinking the orbit. But why outward migration? I need to read up on that too.

[RCgothic]

In the absence of debris friction or third bodies, migrations are caused mainly by tidal forces.

E.g. the sun is spinning faster than Jupiter, tidal drag on the sun causes it to spin slower. The opposite and equal reaction on Jupiter accelerates it along its orbit, causing it to spiral outward.

The same thing is happening between the earth and the moon. The earth is slowing and the moon is getting further away.

Edited July 13, 2020 by RCgothic

[magnemoe]

1 hour ago, RCgothic said:

In the absence of debris friction or third bodies, migrations are caused mainly by tidal forces.

E.g. the sun is spinning faster than Jupiter, tidal drag on the sun causes it to spin slower. The opposite and equal reaction on Jupiter accelerates it along its orbit, causing it to spiral outward.

The same thing is happening between the earth and the moon. The earth is slowing and the moon is getting further away.

However this effect should be pretty weak like solar tides effect on Mars and Earth. 
Now another planet might lift it out, was some talk about solar system had 3 gas giants back at the start but one was kicked out. 
Kind of doubt jupiter went very deep, it would messed up Mars orbit at lest.

[JoeSchmuckatelli]

3 hours ago, Scotius said:

Inwards migration is easy to explain: friction from the material in the planetary disc. There was enough dust and gas in proto-Jupiter's path to slow it down, thus shrinking the orbit. But why outward migration? I need to read up on that too.

I've always thought that a 'spinning accretion disc' would, very quickly after the protostar lit off, become an orbiting dust cloud.  Given that orbital speed is determined by distance, how is friction going to work?  The protoplanet should not be plowing through a virtually stationary dust cloud... It would be the big bad clump of a coorbiting dust cloud. 

 

3 hours ago, RCgothic said:

In the absence of debris friction or third bodies, migrations are caused mainly by tidal forces.

E.g. the sun is spinning faster than Jupiter, tidal drag on the sun causes it to spin slower. The opposite and equal reaction on Jupiter accelerates it along its orbit, causing it to spiral outward.

The same thing is happening between the earth and the moon. The earth is slowing and the moon is getting further away.

The tidal migration of the moon has taken the life span of the moon.  If tidal forces can explain the Jupiter (and Saturn?) outward migration... How we get inner planets at all? (and wouldn't they, also, be migrating outward and thus away from Jupiter like a kid playing can't catch me?) 

[YNM]

3 hours ago, magnemoe said:

However this effect should be pretty weak like solar tides effect on Mars and Earth. 

Actually it is much stronger than the Moon's, and vice versa for the Moon itself (stronger than the Earth's). There's a reason the ocean tide is always synced with the time of solar day, with the Moon making it somewhat higher or lower, not the other way around.

51 minutes ago, JoeSchmuckatelli said:

How we get inner planets at all?

Tidal force is also proportional to the object's size - the larger the object, the stronger the force. Inner planets are tiny compared to the gas giants.

Edited July 13, 2020 by YNM

[JoeSchmuckatelli]

1 hour ago, YNM said:

Actually it is much stronger than the Moon's, and vice versa for the Moon itself (stronger than the Earth's). There's a reason the ocean tide is always synced with the time of solar day, with the Moon making it somewhat higher or lower, not the other way around.

Tidal force is also proportional to the object's size - the larger the object, the stronger the force. Inner planets are tiny compared to the gas giants.

I'm curious about the first part of your reply - having grown up on the beach, I don't remember Noon being the known preferred time to surf... Even during the full or new moon.  Dawn Patrol was always a thing.  (Although I recognize that the winds may have been a bigger factor in this).  So, conceptually, while I know that the sun should deform the oceans to a greater extent than the moon - experientially we always looked at the phase of the moon when prognosticating the waves.  I'm guessing that (from what you write) dawn is likely to be a rising tide and moon phase merely modifies this? 

 

Next - granted that Jupiter is far more massive than anything else, but is it proportionally so much greater than the rocky planets compared to the sun that the tidal effect would move it past and through the rocky planets orbits?  (trying to wrangle why tidal effects would allow reorganization) 

[cubinator]

6 hours ago, Scotius said:

But why outward migration? I need to read up on that too.

The idea is that Jupiter spiraled inwards and messed with the Asteroid Belt for a while, and Saturn pulled it back out before it got too deep.

[K^2]

9 hours ago, RCgothic said:

In the absence of debris friction or third bodies, migrations are caused mainly by tidal forces.

True, but Jupiters' migration would have had to have been more extreme than what can be explained with tidal effects alone. So both friction, read, collisions with smaller things orbiting the Sun, and 3rd body interactions, likely with Saturn and the ice giants, were involved if all of this is correct.

[mikegarrison]

4 hours ago, YNM said:

Actually it is much stronger than the Moon's, and vice versa for the Moon itself (stronger than the Earth's). There's a reason the ocean tide is always synced with the time of solar day, with the Moon making it somewhat higher or lower, not the other way around.

Um ... I live near the ocean and I've seen a lot of tide tables. It's not obvious that "the ocean tide is always synced with the time of solar day". Really big tides are synced to full and new moons, as well as the equinoxes and solstices, so there are definitely interactions with the sun.

Here's a quote from https://oceanservice.noaa.gov/education/tutorial_tides/tides02_cause.html 

Quote

Our sun is 27 million times larger than our moon. Based on its mass, the sun's gravitational attraction to the Earth is more than 177 times greater than that of the moon to the Earth. If tidal forces were based solely on comparative masses, the sun should have a tide-generating force that is 27 million times greater than that of the moon. However, the sun is 390 times further from the Earth than is the moon. Thus, its tide-generating force is reduced by 390³, or about 59 million times less than the moon. Because of these conditions, the sun’s tide-generating force is about half that of the moon (Thurman, H.V., 1994).

Edited July 13, 2020 by mikegarrison

[K^2]

2 hours ago, mikegarrison said:

Um ... I live near the ocean and I've seen a lot of tide tables. It's not obvious that "the ocean tide is always synced with the time of solar day". Really big tides are synced to full and new moons, as well as the equinoxes and solstices, so there are definitely interactions with the sun.

Oh, there are so many factors in local tides that go way beyond gravity. The day-night cycle is a lot faster than lunar cycle, obviously, and water has a lot of inertia, which means the two cycles will not have the same effect even if they were at the same strength. If you're living by the bay, the tides aren't due to water in the bay being pulled by gravity, but hydrodynamic flow of water in the sea/ocean around it, which is driven, among other things, by gravity. But how shallow the water is, how wide the inlet, etc, makes way more of a difference. In general, it's still synced to the tidal rhythm, albeit, with a bit of a lag, unless you're directly on ocean shore. And your highest tide is still going to be around the full or new moon, when Sun and Moon work in tandem rather than in opposition.

That said, this also has negligible impact on rotation of the Earth. The water that's sloshing around bays and shorelines is just not enough mass to make an impact. And the tides in the open ocean are a lot simpler. There is still a factor of water mass, but topography no longer plays any role. And the Sun has significantly greater impact there than the Moon. Not by as giant of a factor as Sun/Moon mass ratio, of course, due to the distance difference, as you indicated, but noticeably. It's probably sufficient to point out that Moon is pulled on by Sun's gravity more than by Earth's, and Moon's pull on Earth is going to be smaller by the mass ratio of these two bodies. (Edit: Corrected by mikegarrison - tidal effect of the Moon is, in fact stronger. See link in quoted post.)

Finally, the tides caused by Sun on Earth have absolutely nothing to do with Earth migrating from the Sun due to tidal effects. You should be looking at tides that Earth-Moon system is causing on the Sun. And that's a whole another story, because the Sun's movement itself is rather complex. It's not even at the center of the Solar System at the moment. So you have to talk about how all of the planets interact with the Sun together to see what sort of tidal effects this results in, and then propagate that back to individual planets to see how much they get pushed around.

Edited July 13, 2020 by K^2

[mikegarrison]

11 minutes ago, K^2 said:

the tides in the open ocean are a lot simpler. There is still a factor of water mass, but topography no longer plays any role. And the Sun has significantly greater impact there than the Moon. Not by as giant of a factor as Sun/Moon mass ratio, of course, due to the distance difference, as you indicated, but noticeably.

I am well aware that beach tides are affected by topography. However, the source I quoted (from the US National Ocean and Atmospheric Administration) definitely states that the moon has twice as big of effect on tides as the sun does (and gives a reference as well as explaining the calculation). So exactly what is your source for claiming the opposite?

[K^2]

24 minutes ago, mikegarrison said:

I am well aware that beach tides are affected by topography. However, the source I quoted (from the US National Ocean and Atmospheric Administration) definitely states that the moon has twice as big of effect on tides as the sun does (and gives a reference as well as explaining the calculation). So exactly what is your source for claiming the opposite?

You're right. It's an inverse cube. Moon wins. I was extrapolating from actual movements of water levels in deep ocean and, you're going to laugh at this, but I forgot that the Earth spins. When I was extracting relative strengths, I modeled it as Sun going around the Earth in 24h, and Moon going around the Earth in 27 days. When, of course, relative to Earth, Moon goes around in under 25 hours, so the two periods almost match, with envelope modulated by the beat frequency.

[YNM]

@mikegarrison You're correct. I guess something you did only once 5 years ago did no justice to memories XD Seeing the tide tables now also proves it. Thanks for reminding me, at least I wasn't doing an actual port with that mistaken fact in mind XD

Although it's something to remember that the Sun also generates a fair amount of tidal forces. I mean, the Earth is compact; for a less compact object like a Gas Giant, the effect might be more significant.

@JoeSchmuckatelli sorry for giving you the wrong facts on that one.

Edited July 15, 2020 by YNM

[JoeSchmuckatelli]

7 hours ago, YNM said:

@mikegarrison You're correct. I guess something you did only once 5 years ago did no justice to memories XD Seeing the tide tables now also proves it. Thanks for reminding me, at least I wasn't doing an actual port with that mistaken fact in mind XD

Although it's something to remember that the Sun also generates a fair amount of tidal forces. I mean, the Earth is compact; for a less compact object like a Gas Giant, the effect might be more significant.

@JoeSchmuckatelli sorry for giving you the wrong facts on that one.

'salright!  Made me think there for a moment - and I too appreciate @mikegarrison' s posted info that confirms my feels about the waves I grew up with.

 

Back to the Wandering Jupiter - so... I can see a body like Jupiter having its orbit changed by interacting with another body - but my very limited knowledge of the mechanics involved suggests that the orbital change would happen once and then the other body gets flung from the system or into the sun. 

With the friction idea - again driving through a dust cloud and having bazillions of dust-planetesimal sized interactions could be an answer, but trying to guesstimate why - in that scenario - Jupiter would have a largely stable orbit while all the dust particles would have to have nearly perpendicular elliptical orbits doesnt make a lot of sense.  The planets we have all are pretty similar in that their orbits are stable and in the same direction - an easy projection then is that the proto disk material also orbited the sun in a similar way... With the 'clearing the orbit' period resulting in the heavy bombardment - but even then - is there enough material to pull proto Jupiter inward and then have tidal forces send it back within the lifetime of the solar system? 

[Bill Phil]

5 hours ago, JoeSchmuckatelli said:

Back to the Wandering Jupiter - so... I can see a body like Jupiter having its orbit changed by interacting with another body - but my very limited knowledge of the mechanics involved suggests that the orbital change would happen once and then the other body gets flung from the system or into the sun. 

With the friction idea - again driving through a dust cloud and having bazillions of dust-planetesimal sized interactions could be an answer, but trying to guesstimate why - in that scenario - Jupiter would have a largely stable orbit while all the dust particles would have to have nearly perpendicular elliptical orbits doesnt make a lot of sense.  The planets we have all are pretty similar in that their orbits are stable and in the same direction - an easy projection then is that the proto disk material also orbited the sun in a similar way... With the 'clearing the orbit' period resulting in the heavy bombardment - but even then - is there enough material to pull proto Jupiter inward and then have tidal forces send it back within the lifetime of the solar system? 

I believe the idea is that as Jupiter gained mass it gained mass from material that wasn't quite in orbit around the proto-sun - the gas was still capable of supporting itself against gravity to some extent due to its own internal kinetic energy. Then the average angular momentum after each collision is not high enough to maintain the current orbit, so Jupiter falls toward the proto-sun, experiencing a kind of "drag". Keep in mind that Jupiter wasn't at its current mass, it gained mass throughout the entire process. Some of the material it collided with was captured and some wasn't. This is also part of the explanation for why the asteroid belt has so little mass (getting kicked out or getting absorbed by Jupiter), and even related to Mars having less mass than what might be expected. So there's enough material - much of it is in Jupiter today.

The Sun was likely rotating faster billions of years ago - and since Jupiter was closer the tides would have been stronger. So it could potentially bring Jupiter to its current orbit. The tidal acceleration affect would have been stronger initially since Jupiter would have been closer and the Sun would have been rotating faster. Though I suspect this may not be entirely enough - some gravitational effect from Saturn likely also factors in.

It's also possible that Jupiter didn't migrate that far into the inner solar system, instead reaching an equilibrium point where the drag was much lower.