Jupiter's Orbital Velocity & Equatorial Velocity cancel?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by nebel, Jul 31, 2017.

  1. nebel Registered Senior Member

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    It appears that the retrograde motion on the sun -facing surface at the equator of rotating Jupiter is ~ equal to the overall orbital prograde motion. Any significance, like zero effects on magnetic or space drag fields? thank you.
     
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  3. origin Trump is the best argument against a democracy. Valued Senior Member

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    I am not sure what you mean by this. Are you saying from the vantage point of the sun that Jupiter would have retrograde motion?
     
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  5. nebel Registered Senior Member

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    origin, surprisingly, Saturn too has the two velocities match within 2% ~ 10 km/s wow! no, what I am inquiring about is, that as the planets moves on their prograde orbit, the anti-clockwise rotation would have the sunny side move in the opposing direction , the night side of course moves in the direction of the orbit movement, doubling the apparent the surface speed. Since for Jupiter and Saturn, the two velocities are closely matched, the planet moving forward, and the sunny rotation side moving contrary to the orbital motion, It would be akin to putting a tire mark in the snow on the road, not a skid mark.This situation should have effects on viewing, the fields without shear. stability.
    On a moving car, similarly, the tire , where it touches the road, rotates backward at~ the same speed that the car advances. giving a temporary zero velocity picture, imprint, left behind on the road, so? thank you.
    PS:. A camera locked onto feature at the equator (disallowing wind speed) should have that image blur free, without tracking the total planet.?
     
    Last edited: Aug 1, 2017
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  7. nebel Registered Senior Member

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    I inquired about a related situation before. Earth and Venus the closest planets, have their mutually visible surfaces move in the same direction, albeit at different speeds. because Venus has a retrograde spin, they rotate like one is being dragged along by the others motion. not exactly mashing gears like the Jupiter ,Saturn orbit rotation match.
     
  8. James R Just this guy, you know? Staff Member

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    Can you please give the figures that support your claim that the equatorial velocity is approximately equal to the orbital velocity for Jupiter and Saturn?
     
  9. nebel Registered Senior Member

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    james, i am computer illiterate, but here are the copy & pastes from wiki headlines.
    Jupiter from Wikipedia:
    Equatorial rotation velocity
    ‎: ‎12.6 km/s; 45300 km/h
    Average orbital speed‎: ‎13.07 km/

    Saturn from Wikipedia:
    Equatorial rotation velocity
    ‎: ‎9.87 km/s (6.13 mi/s; ...
    .Average orbital speed‎: ‎9.69 km/s (6.02 mi/s)

    The surfaces are nearly standing still at noon, as the planet's surfaces rotate and revolve in opposite directions. is this new to you? within ~4% Jupiter, ~2% Saturn
    perhaps such a stationary environment makes it easier to build delicate rings?
    certainly would maximise solar radiation capture, points lingering in max incidence sunshine?
     
    Last edited: Aug 2, 2017
  10. James R Just this guy, you know? Staff Member

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    I don't really see why this fact would be important. All it says is that at any instant a point on the equator of the planet, on the imaginary line joining the Sun to the planet, is approximately at rest as viewed from the Sun. But the planet is still rotating, so after a short time later, that particular point will be moving again with respect to the Sun.

    If you were to stand on the Sun and watch a fixed point on the equator of the planet (i.e. a point that rotates with the planet), then during a half-rotation period of the planet (half day), you'd see that point moving fast (at the orbital speed of the planet) at "dawn", then slowing to a stop at "noon" (planet time), then apparently speeding up again until "sunset". You'd be watching the addition of the planet's orbital velocity being constantly added to a projection of the point's rotational velocity in the direction perpendicular to the line of sight.
     
  11. nebel Registered Senior Member

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    James, here you have an area, that actually is nearly stationary, exposed to the distant sun, a whole dayside that moves on average slower , for a longer period, and that is not important, has no ramifications? on like any conditions related to the sun's effects? have you seen this tackled before?
    Imagine an Earth day where the sun would linger at noon, rises and sets almost suddenly?
    It would be great in the winter, and of course the solar radiation is diluted at 5 and 10 AU. Do these surfaces gather more solar energy because of the velocity cancelling arrangement?
     
    Last edited: Aug 2, 2017
  12. origin Trump is the best argument against a democracy. Valued Senior Member

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    What sort of ramification do you think there are. I don't see anything of particular note.
    It does occur to a lesser degree. That is why after the winter solstice that the lengthening day does not have the same minutes of increase in sunset as the minutes of decrease in sunrise.
    I wouldn't think so.

    You get all wrapped up in this type of stuff and it ends up being nothing but a type of numerology.
     
  13. nebel Registered Senior Member

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    Last edited: Aug 2, 2017
  14. origin Trump is the best argument against a democracy. Valued Senior Member

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    So what. If we had the orbit of venus one side of the planet would be hot as hell and the other cold. what is the big deal?
    Not sure why think that is such a big deal. It is interesting but you seem to be thinking it is earth shattering. [shrug].
     
  15. nebel Registered Senior Member

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    Janus, I read your refutation in the' Joshua' entry of the religion forum, but are replying here, beyond religion. 0f course the angle through which the sun's image rotate is different with a 10 hour Jupiter versus a 24 hour Earth day. But
    Why would a change in velocity of an observer on, or above the surface not change the length, direction of observation?
    We can fly planes in n everlasting sunlight eastward at the speed of sound. Would the retrograde spin motion of the Jupiter & Saturn equatorial surfaces, not be the equivalent of hovering under a point light source?
    Not that a point on these planet's surfaces will stay in sunlight forever, but at the moment of maximum apparent heights, the motions of revolution and rotation should cancel or?
    Any incoming radiation must have a motion bias any way, but correcting for that, that apparent motion varies from full orbital velocity at morning (facing into orbit direction) to zero at noon,. or?
     
  16. Janus58 Valued Senior Member

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    The situation you are talking about is like this. The planet is rolling along an imaginary circle as it travels around the Sun.

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    But in this situation only points that are on that circle can every be said to have zero movement with respect to the surface, and that is when the planet is touching that point of the circle.

    Here's the same situation as seen from the frame of the planet and with some additional markers placed at points along the radius of the circle.

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    Note how just the marker on the circle moves in, and for a brief instant is motionless with respect to the center before moving off again. None of the other markers at different radii of the circle do this they all, including the center of the circle where the Sun would be, are in constant motion. The only reason that one point does "stop" for an instant is that, during that one moment, its tangential speed and distance relative to the center of the planet is equal to that of the surface of the planet and thus their instantaneous angular velocity are the same in that instant.[/I]
     
  17. nebel Registered Senior Member

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    370
    Janus58, you nailed it , thank you. I hope everybody reads that. Can that image, link be made openable?
    My point is, that the circles of the orbit and equator touch not only only at a point on a line between the sun and the planet, the situation is more fluid, comparable to a tire rotating, flattening out, what with eccentricities, bari centers, angle of incidence of photons, the solar wind magnetism and other variables.

    Using the car wheel analogy, the velocity at the surface of the rolling wheel you mentioned goes from double the orbital velocity at night to zero at the area of contact, but not in a jerky zero to max. movement, but in beautiful gradual accelerations. This near zero velocity interaction between the ~ stationary "road", (the solar energized inner planetary field) and the constantly rotating planet, must have been explored before and carry even a name, similar to the related Yarkovsky effect, carrying absorbed solar energy energy on a rotating object.

    I can not believe that this is only a 'compass and straightedge' geometric exercise, but that that the exposed area of contact between these speeding planets, and the active solar system field should be ~ at rest in these two cases, carries physical consequences. The zero shear point being theoretically at the equator, but growing to that point from the east, west. north and south limits of the illuminated areas.

    Zero shear implies stability ( where the tire hits the road) and I am thinking of the undisturbed rings of Saturn, the longtime atmospheric features on Jupiter. Could these structures exist if there would not be this match of spin and orbital velocities? If they could not, would you not have a contributing cause and effect link.? or?
     
    Last edited: Aug 6, 2017
  18. James R Just this guy, you know? Staff Member

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    nebel:

    The stationary point on the planet's equator is only instantaneously stationary, and only with respect to the Sun.

    If you're sitting on the surface of the planet, and the local "day" is 10 hours long, let's say, then the Sun will be seen to track across the sky at a regular rate, and you'll notice nothing special at noon when the Sun is directly overhead. In particular, you won't see the Sun apparently pause in the sky when it is overhead, then start moving again. Janus58's second animation above clearly shows that.

    Only it doesn't work like that. The Sun's rate across the sky on any given day is constant (assuming you're on the equator, and the equatorial plane of the planet is lined up with the ecliptic, etc.)

    The answer to that is: no.

    The primary reason why we get more solar energy in summer than in winter is due to the tilt of the Earth's axis with respect to the ecliptic.
     
  19. nebel Registered Senior Member

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    Can these images be made clickable for google chrome? thanks.
     
  20. nebel Registered Senior Member

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    James, I like to see that animation to convince me , and other sceptics.

    Let us assume you attached a camera to the wheel of a car, chariot, and had it measure the movement of near traverse lines on the road, that like rays or spokes point to the sun on the horizon, On top of the turning wheel, the lines would appear as a blur, racing in short time intervals at twice v. On the front down quarter turn, the camera would traverse the spaces between the lines at v but slowing, downward , approaching the area of contact, the line would come to a standstill time interval at longest. On the upward leg, the trailing side, the camera would see the near lines passing at v again. Parallax would show the sun moving apparently in opposite direction to the foreground, irrelevant here.
    Time between lines, top= 1/2 t ; front and back: t ; bottom contact= 2 times longer? or

    The crucial point I like to have elaborated on is, that at the point of interaction of rotating wheel or J&S equator regions, there is a unique, maximum time, no shear situation, That must have consequences, because that is the region affected by the sun in many ways. Since the effect is max in the center of the planets' faces, but neutral in the west, east and north, velocity gradients would show their effect. perhaps Jupiter banded latitudes reflect that?
     
    Last edited: Aug 6, 2017
  21. nebel Registered Senior Member

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    370
    Can I propose a thought experiment here?
    Assume that Jupiter or Saturn were transparent spheres, moving in their orbit during one revolution through a given angle containing a given amount of solar photon energy, particles, magnetic force etc. Is not
    the night (inner) side, per area unit, exposed to that influence only half the time than the leading (morning) and trailing (evening ), sides? because it goes at~ twice the orbital velocity (a prograde rotation in a prograde orbit) --through that orbital segment angle? with it's fixed, given effect?--- half the exposure time, = half the effect? and does not
    The sunny, outer side receive ~ 2 times the solar package, since it recedes by its rotation from the orbital direction at the same speed that the planet as a whole advances? twice the exposure time= twice the effect?. actually a fourfold lower difference between the imaginary inner night side and the outer surface. ....refutations please. preferably supported by clickable diagrams. for all to see.

    If my conjecture is correct, the rate of prograde rotation would ~ double the solar effects on these planets compared to a ones with a theoretical non-rotating face? or?
     
    Last edited: Aug 8, 2017
  22. nebel Registered Senior Member

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    questions on consequences of the line of sight mutual cancellation of orbital and rotational velocities.:---Different emanations from the sun reach into space at different angles, as made evident by the different directions of particles, radiation of comets' tails, but somewhere in the Jupiter & Saturn environment no shear interactions occurs because a given point on their surfaces does not advance against those solar effects. or?
     
    Last edited: Aug 8, 2017
  23. nebel Registered Senior Member

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    James R wrote: "The answer to that is: no.

    The primary reason why we get more solar energy in summer than in winter is due to the tilt of the Earth's axis with respect to the ecliptic.[/QUOTE]

    So true, but I was not referring to the Earth, or Uranus, the real extreme tilter, but Jupiter, Saturn , where the distribution of incoming solar influences must be affected by the zero movement , extended exposure times during the cancellation of the mutual, opposing orbital, and rotational velocities, or?
    The other question besides distribution, length of exposure, is of course, the near no shear interface between planet and the inner solar field.
     
    Last edited: Aug 8, 2017

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