Uranus is prograde or retrograde?

Uranus's tilt is 98°. Astronomers (many of them) still consider its rotation to be prograde (west to east) even though it is tilted a good 8° below the plane. This would mean its north pole is 8° below the plane, and the south pole 8° above the plane. Many others consider the opposite: its rotation is retrograde having a tilt of 82°, and the north pole would therefore be above the plane (sort of like Venus with an extreme tilt) which would look more correct to the standard order. 

My question is, why can't astronomers decide what this magnificent large planet be? A prograde or a retrograde? This creates nothing more than confusion among scientists.

Your opinions please.

4 Answers

  • 1 month ago
    Favourite answer

    Unfortunately for us (who try to explain such things), the definitions have changed over time (at least twice during my lifetime).

    It used to be that the "North Pole" of a planet was defined as the one above which the rotation would appear counterclockwise (i.e. to the left). Thus, the North pole of Venus would point "down" when compared to our own.

    In that sense, our Galaxy's "Galactic north pole" is pointing "down".

    Then someone thought that we could reduce confusion by dividing the celestial sphere in two halves, using the ecliptic.  Any pole that points towards the "north" half of the celestial sphere, would be called a north pole.

    Therefore, from its new Galactic north pole, the Galaxy's rotation is retrograde. Under this definition, the uranian rotation is retrograde.

    The confusion was not reduced.

    • ANDY
      Lv 5
      1 month agoReport

      Thank you Raymond.

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  • 1 month ago

    Like any other body, it is which way up ypou are Observing

     When its South Pole is facing us it is Prograde and other ways Retrograde

    Compered to other Planets it is actually Upside Down

    Only its South Pole reacts to Sunlight when it is at Perihelion

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  • 1 month ago

    Actually it doesn't create confusion among the pros.  Why?  Because you can choose whichever way you'd like it to be.  But then, which is what we've all learned in freshman physics, be consistent with all the other directions in your problem or study.  You see, all you're doing when you pick a direction or rotation to be plus or minus, for example, is defining the coordinate system.  It won't change the physics.

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    • oldprof
      Lv 7
      1 month agoReport

      Andy one thing about the STEM community; they're hard to move away from the way they learned it in school. Prime example, EE guys are still plotting electrical current from the anode to the cathode. And that's patently wrong, that's not the physics.  But that's the way they learned it in HS.

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  • 1 month ago

    My opinion is that it's retrograde... Maybe the IAU can make the determination that if the pole that rotates counter-clockwise is 'below' it's plane of orbit, the planet has retrograde rotation...

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