# Thread: Why the Jupiter rotates on its orbital plane?

1. The only Jupiter – the hugest planet of our solar system – rotates on its orbital plane. What is the reason for this interesting anomaly?

2.

3. What do you mean? Are you confusing this with Uranus?

4. No, I don’t . I mean that rotational axis of Jupiter is almost perpendicular to its orbital plane (axis of Uranus lies near its orbital plane). This arrangement is more probability.

5. Why do you think so? Uranus is the exception in the solar system. The rotational axes of the all the other planets are more or less perpendicular to the orbital plane. This means that the vectors of the angular momenta of the orbital and rotational motion are almost aligned. This is a result of the formation process of the planets. Any deviation could be explained by gravitational interaction with other bodies in the solar system or massive impacts.

6. I have different opinion. Let’s consider the Earth, for example. Admit, that any orientation of it’s rotation axis has equal probability (relatively for “true” orientation). Then so inclination as Jovian (3 degree from “vertical”) means, that ferrule of axis leans out into circle which radius is equal to 100 km. If the axis is oriented as axis of Uranus, then ferrule will be lean out into broad belt between 9 degree north and 9 degree south. And total area in the second case is incomparable huger.

7. Sorry, but I have difficulties understanding what you are trying to say.

8. The Jupiter is not an usual planet, but the rest of brown draft. While it was forming (When its volume was incomparable large) it collide with the “protoSan” (when it also was forming and also was large, then now). This collision had orient the axes of the Jupiter and the San as now. The biggest part of brown draft had destroyed into protoplanetary disc. The other planets had formed from substance of this disc.

9. Originally Posted by KrupS
Admit, that any orientation of it’s rotation axis has equal probability (relatively for “true” orientation).
I thinkk your argument fails because of this faulty premise. The preferred orientation is at right angles to the original orientation of the accretion disc. The angle is subsequently changed (and changes) in response to impact and tidal effects. Dishmaster already pointed this out.

By brown draft, do you mean brown dwarf? Jupiter is much too small to be a brown dwarf.

10. I think that nobody knows low level mass of brown draft. Probably it is equal to Jovian mass or slightly bigger. This limit is estimated for isolated brown draft. But if it forms near a star, it may reduce due to interaction with the star such as star wind.
Initial angular momentum of any planet is equal to zero. The final moment is the result of accidental impacts.

11. I understand the mass limit for brown dwarfs is generally set at around 10 x Jupiter Mass. Solar wind is effective at removing gas from the accretion disc, but I don't think there is any evidence that the proto-sun could substantially reduce the mass of brown dwarf, even in its T-Tauri stage. It would be just to big.

What makes you think the angular momentum of planets starts at zero? This icontrary to both evidence and theory.

12. I completely agree with You about nothingness influence of star wind. But stars (and drafts) born from huge gas-dust clouds, which are bigger then total solar system. If on this early stage the impact between the Jupiter and the Sun had been the Jupiter might lose (for instance) 9/10 it’s start mass. In this case our Jupiter is only the rest of giant protoJupiter.

13. Originally Posted by KrupS
The only Jupiter – the hugest planet of our solar system – rotates on its orbital plane. What is the reason for this interesting anomaly?

What anomaly? Jupiter has an axial tilt of 3.13°, not far from Ceres with a tilt of 4°. Besides that, Jupiter doesn't even have the smallest axial tilt. Venus axis is only tilted 2.6° from being perpendicular to its orbital plane, and Mercury has a orbital tilt of 0.01°.

14. I have ignored the Mercury and the Venus, because ,in fact, they have not rotation not at all (theirs very week rotation is the rest of initial one.) Theirs rotations had reduce due to tidal force of the Sun (both planets are in spin-orbital resonances).
From remaining 6 planets namely the largest – Jupiter have vertically orientation of its axis. The Ceres is only one of thousands and millions rocks(also the biggest), moving between orbits the Mars and the Jupiter.

15. Originally Posted by KrupS
I have ignored the Mercury and the Venus, .....
I think you are being very selective in your use of data. I am also not clear what you think is wrong with current theories of planetary formation. And you haven't explained what makes you think planets start out with zero angular momentum.

(I don't want to be rude , but could you also stop calling brown dwarfs brown drafts. It is a little distracting . Thanks.)

16. Diameters of celestial bodies are so tiny in comparison with dimension of solar system, then this bodies, in fact, are mathematical points of unimaginable tiny. In accordance with modern hypothesis of planet formation on early stage the planets grows by means of many small collisions which mast to compensate each other statistically (collisions can be from different sides with equal probability).
Lately planets can get non zero moment as a result of singular collision with very large body. Therefore, finally result will be arbitrary orientation of axis.

17. Originally Posted by KrupS
In accordance with modern hypothesis of planet formation on early stage the planets grows by means of many small collisions which mast to compensate each other statistically (collisions can be from different sides with equal probability).
No. This is where I believe you are mistaken. This would only be true if the collapsing cloud possessed no net angular momentum. The modern hypothesis of planet formation argues for a rotating cloud with definite, significant annular momentum and so the collisions are not from random directions with equal probability.

18. Originally Posted by KrupS
In accordance with modern hypothesis of planet formation on early stage the planets grows by means of many small collisions which mast to compensate each other statistically (collisions can be from different sides with equal probability).
This is only partly true. Yes, planets grow by coagulation from very small dust particles up to planetesimals and eventually entire planets. But this process does not happen in a quiescent environment but in the protostellar accretion disc. May I direct your attention to a related thread? A few posts there describe the production of eddies inside the accretion disc from which the protoplanets form. They all have a natural angular momentum with its momentum vector and the one of the disc well aligned. So, the starting condition is that all (proto-)planets have roughly the same axis orientation. The final differences may be a result of dramatic impacts of asteroids or comets on those already fairly evolved objects. And the higher the angular momentum of the planet (roughly a product of spinning speed and mass distribution) the smaller is the impact on the rotation axis.

You can do your own small experiment to test this. Take something that spins (spinning top, gyro, bicycle wheel) and put it into spinning. Then try to change its orientation by hitting it. You will notice that the impact is weaker the faster it spins. So, it is difficult to change the axis of a rotating object - especially when the momentum of the impacting bodies is small compared to the angular momentum of the spinning object.

19. Also we don’t understand how planets of our solar system hav got their angular momenta, but nothing prevents us to consider this process from the position of statistics. From common sense we may conclude, that rotational axis of each planet is independent from axes of others planet. Let’s denote probability of “vertical” axis as “p”, and of any other orientation – as “q=p-1”. Then probability of total orientation mast be equal = p*q^5 (the only biggest planet is oriented perpendicular, and all others – in different directions). Maximum of this probability makes, when p=1/6 and q=5/6. The probability is equal approximately 0,05. Thus the theory of probability supports my hypothesis about peculiarity generation of the Jupiter.

20. Originally Posted by KrupS
Also we don’t understand how planets of our solar system hav got their angular momenta, .
Surely we do understand how the planets got their angular momenta:
1) Derived from the angular momentum of the parent gas cloud and subsequent accretion disc.
2) Significanlty modified by collision.
3) Further modified by tidal interaction transfering angular momentum.

21. I admire with your perceptions. But can you answer to me why namely and the only Jupiter, but no the other planet (say the second – Saturn) possesses the above-mention peculiarity?

22. Originally Posted by KrupS
I admire with your perceptions. But can you answer to me why namely and the only Jupiter, but no the other planet (say the second – Saturn) possesses the above-mention peculiarity?
Jupiter is the most massive planet by far in the solar system. The resulting inertia makes it less susceptible to changes of the angular momentum than other planets. You might remember the impact of the comet Shoemaker-Levy a few years ago. It was truly a huge impact, but it didn't change Jupiter's rotation axis a bit. If that had happened on Earth, the result would have been different.

23. Well, it seems, that we have gone to blind alley for this question. Each side is sure with its rectitude. Let’s go to this problem from the other hand. Let’s consider a question – why the Jupiter and the Saturn are very different with regarding chemical substances. This difference evince distinctly in comparison of theirs densities and densities of theirs moons.

24. Originally Posted by KrupS
Well, it seems, that we have gone to blind alley for this question. Each side is sure with its rectitude. Let’s go to this problem from the other hand. Let’s consider a question – why the Jupiter and the Saturn are very different with regarding chemical substances. This difference evince distinctly in comparison of theirs densities and densities of theirs moons.
How is this question related to your original question?

I think you've decided that Jupiter is "special" and are cherry picking the evidence to support that.

25. It is difficult to explain difference between densities of Jupiter and Saturn if each planet have formed the same manner. But if we assume, that the Jupiter is a unsuccessful brown draft, this question solves easily. The initial gas-dust cloud, from which the brown draft condenses, consists of 99 % of gas and only 1% of dust. Pressure of gas that withholding the gas from falling into the center of cloud, does not disturbs downfall for hard particulars. As a result the core of cloud enriches by rocks and metals. When the parent clouds of the Sun and the Jupiter collide, the cover of the Jupiter dissipates, while the core conserves. It is the reason for the Jupiter and its satellites have more density, then the Saturn and its moons.

26. Originally Posted by KrupS
It is difficult to explain difference between densities of Jupiter and Saturn if each planet have formed the same manner.
They may not have formed in an indentical manner and they did not form at an identical distance from the sun.
Originally Posted by KrupS
But if we assume, that the Jupiter is a unsuccessful brown draft, this question solves easily.
There is no reason to assume this.
Also, could you possibly use the phrase brown dwarf, not brown draft. I understand political correctness prohibits the use of the term dwarf when referring to persons of limited stature. It is still acceptable in astronomy and in Lord of the Rings.

27. Originally Posted by KrupS
From common sense we may conclude, that rotational axis of each planet is independent from axes of others planet.
I'm sorry KrupS, but this is not common sense, in fact, with any theory of celestial mechanics this is, strictly speaking, non-sense because it does not take into account our theories of planetary formation.

As others here have tried to make clear:

1. Jupiter is way below the mass limit for a brown dwarf;

2. It is likeliest that a planets plane of rotation will be the same (or similar to) its orbital plane;

3. The brown dwarf issue is, if you'll parden the mixed metaphor, a red herring, because even if the solar system is, as you appear to think, an abortive attempt at a twin star system, the law of conservation of angular momentum suggests that we'd expect both stars to have rotational planes more or less in line with their orbital planes.

4. As others have, again, pointed out here: the larger an obeject, the msaller the chance that a collision will knock it off, or far off, its axial orientation.

Have you thought about these things at all, or is this just a hobby-horse of yours?

cheer

shanks

28. Originally Posted by Dishmaster
Originally Posted by KrupS
I admire with your perceptions. But can you answer to me why namely and the only Jupiter, but no the other planet (say the second – Saturn) possesses the above-mention peculiarity?
Jupiter is the most massive planet by far in the solar system. The resulting inertia makes it less susceptible to changes of the angular momentum than other planets. You might remember the impact of the comet Shoemaker-Levy a few years ago. It was truly a huge impact, but it didn't change Jupiter's rotation axis a bit. If that had happened on Earth, the result would have been different.
Originally Posted by KrupS
Well, it seems, that we have gone to blind alley for this question. Each side is sure with its rectitude. Let’s go to this problem from the other hand. Let’s consider a question – why the Jupiter and the Saturn are very different with regarding chemical substances. This difference evince distinctly in comparison of theirs densities and densities of theirs moons.
What we're dealing with is what is known to staticians as the "Law of Large Numbers". This law runs contrary to ordinary intuition but has been confirmed with sufficient practical regularity in the Underwriting departments of insurance companies the world over, that only the most stubborn critic would doubt it.

The idea is that, if you roll a sufficiently high number of dice, the % variation among outcomes becomes very very small. Like, if you roll a million dice, and measure the % difference between your outcomes of "1" and "6", you'll find that the % difference between them is very small every time you do the experiment.

Jupiter is large enough for this effect to matter. It gets hit by so many asteroids that the random directions from which the impacts occur will always balance out over time. Earth, on the other hand, has too few die rolls happening to get that law of large numbers effect going, so our die rolls don't balance out like Jupiter's die rolls do.

29. Suppose, We Have solved the first problem – about rotation the Jupiter. But the second part – about anomaly density of Jupiter and it’s satellites stays unsolved.

30. At first sight the questions about Jovian rotation and density seems negligible local problems. They were not even considered by researches of planets seriously. But this is not the only “trinket”, that is ignored by specialists. Specialists omit whole logical chain, consisting of this omissions – clues for discovering the mystery of the origin of our solar system.

31. It may seems quietly impossible that one dilettante have solved the problem , which whole professional collectives were not able to solve for centuries. But wonders sometimes take place. Let’s remember about a dilettante whose name Sherlock Holmes, which won the professional Scotland Yard inspector Lestrade.

32. Wasn't Sherlock Holmes a fictional character? (Sir Arthur Conan Doyle's invention)

33. Of course, this was a joke. But as says a Russian proverb «В каждой шутке есть доля правды», as may be translate to English approximately as “Each joke holds some truth”. (Does such proverb exist in English?” Planetary science is reality closely to detective practice, then to usual science.

34. What is the difference of planetology and others sciences? In physics or chemistry we usually can make an experiment or series of experiments for examination a hypothesis. In planetology we can’t build a huge gas-dust cloud and supervise it’ evolution for a time of millions years. We can only use weekly footprints of the process of generate of our planetary system. A detective is in similar situation. A criminal, as a time (4,6 billion years) makes all as possible for cleaning any corpus delicti. For this reason we must be very carefully for any detail.

35. There is another common property for planetology and criminology – both are many-sided branchs of practice. As soon criminology deals with many sides of human practice, as planetology deals with different properties of planetary system. Crème is investigated by one detective (also with assistants). The history of solar system is investigated by many narrow specialists (in cosmochemistry, celestial mechanics, meteorite science end so on). And this investigation is similar to investigation of elephant by blind men http://en.wikipedia.org/wiki/Blind_Men_and_an_Elephant

36. The same is true of geology and to a lesser extent some fields of biology. Typically experiments cannot be designed to test hypotheses, but we must consider past events as the experiments and present conditions as the result of those experiments.

However, we can design experiments that explore specific aspects of a topic. Thus laboratory tests can reveal what conditions will lead to the formation of specific minerals and mineral combinations. When combined with knowledge of meterite composition we can deduce the environment of the accretio disc from which the planets formed.

In addition powerful computers allow us to run finite element analysis simulations of the physics of a collapsing dust cloud.

37. The history of my idea began from trying to answer for a question “ Why satellite systems of giant planets – Jupiter, Saturn and Uranus are so similar to whole solar system, also scales of space and time of this systems differ for many times.” I assumed that it was able to explain by existence of extremely simple but universal method of generating all such systems.
All this systems have a following common property: commensurability at orbital periods of theirs celestial bodies - http://en.wikipedia.org/wiki/Commensurability_(astronomy) . I have discovered another commensurability, illustrating by follow example:
If a same body revolves in such manner, that its orbit is tangent to orbits of the Earth and the Venus, that each the first years it will meet with the Earth (that body will be in orbital resonance http://en.wikipedia.org/wiki/Orbital_resonance 4/5 with the Earth).
When I understood the reasons of this two type of astronomical resonance, I get my theory.

38.

39. I don’t understand, why You repeated my reference
with a tale of points. Perhaps, You think, that I make nothing new, and my example is well known for centuries resonance 8/13 Venus-Earth (8 years of the Earth = 13 years of the Venus). But my example is refer to quite different, unknown for now type of relationship – not between two planets (or moons), but between a planet and virtual asteroid (or spacecraft), moving between orbits of two planet. My example means, that if we throw a spacecraft to orbit of the Venus, it (if it misses the Venus) through 5 revolutions will meet with the Earth (through 4 years).
It is really new type of relationship.

40. Originally Posted by KrupS
It is really new type of relationship.
Is this not the same relationship that allowed the Mariner spacecraft to make multiple passes of Mercury?

41. No, it isn’t. I consider somebody, flying in such manner, that perihelion of its orbit is on the orbit of Venus, and aphelion is on the orbit of Earth. Then semi-major axis of its orbit is equal to semi-sum of the radii of orbit the Venus and the Earth (0,723a.u. and 1a.u. (by definition) sufficiently).
We can find the period of revolution of this body in accordance with Kepler's third law "The square of the orbital period of a planet is directly proportional to the third power of the semi-major axis of its orbit. Moreover, the constant of proportionality has the same value for all planets."
Semi-major axis is equal to (0,723+1)/2=0,861. If we take square root of the third power of its number, we get a number extremely near to 0,8. (0,861^3)^(1/2)=0,8 repeat this, pleas.

42. http://www.cnn.com/2004/TECH/space/0...ion/index.html
Inside the giants Puzzling differences in Jupiter and Saturn

This is another confirmation of my opinion.

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