# What's your interpretation of a sphere "spinning clockwise"? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [March 26, 2024, 4:07pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397 "2024-03-26T16:07:05Z")\ **Posts on this page:** 15\ **Page:** 2
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 26, 2024, 11:14pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/21 "2024-03-26T23:14:33Z")
> [@DPRK](#): > > Solar north (i.e. Earth’s north, we all know which half of the universe we are talking about) We do? Are we talking about the solar north half, or the Earth’s north half? They differ by 23.5º. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 26, 2024, 11:19pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/22 "2024-03-26T23:19:23Z")
I may be misremembering, but there is a fixed plane perpendicular to the angular momentum of the Solar System, and the North side is the one in which the Sun’s and Earth’s poles lie. So we are talking about the Solar north half, basically. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [March 26, 2024, 11:22pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/23 "2024-03-26T23:22:22Z")
> [@LSLGuy](#): > > The circle/sphere distinction is incorrect. If you look at a conventional analog clock from the back side, the hands move in a counter-clockwise direction. It is only because you assume the context of looking at it from the front that you think you know what the word “clockwise” represents. > > Speaking precisely about any rotation involves defining an axis and defining one end of that axis as the special reference one. There is zero difference in that between a spinning disk, a sphere, or even a 4D hypersphere. On my sailing trip, I was told to always coil ropes in a clockwise direction. These were twisted manilla ropes, and each coil imparts some extra twist into the rope fibers. Apparently a counter-clockwise coil imparts too much twist into the rope. That never made complete sense to me. A clockwise coil viewed from above, would be a counter-clockwise coil when viewed from underneath looking up. For once in my life, I kept my mouth shut and did as I was told. ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [March 26, 2024, 11:30pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/24 "2024-03-26T23:30:22Z")
> [@Hampshire](#): > > I always thought a neat novelty item to have would be a globe of the earth with the south pole on top and all the text upside-down. This? > **[Buy Upside Down World Map | World Wall Map](https://www.mapsinternational.com/upside-down-political-world-wall-map.html)** > > Our upside down world map helps appreciate that the world is spherical rather than flat. You can buy this upside down map poster for your home & office decor. markn\_1 ninja’ed me on the globe. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 26, 2024, 11:36pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/25 "2024-03-26T23:36:09Z")
> [@Robot\_Arm](#): > > That never made complete sense to me. A clockwise coil viewed from above, would be a counter-clockwise coil when viewed from underneath looking up. For once in my life, I kept my mouth shut and did as I was told. But you’re coiling it from above, which adds the needed asymmetry. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [March 26, 2024, 11:36pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/26 "2024-03-26T23:36:38Z")
OK, I looked up the Report of the IAU Working Group on something-or-other, and it says > **[WGCCRE2015reprint.pdf](https://astropedia.astrogeology.usgs.gov/download/Docs/WGCCRE/WGCCRE2015reprint.pdf)** > [@](#): > > The north pole is that pole of rotation that lies on the north side of the _invariable plane_ of the solar system. Its direction is specified by the values of its right ascension \alpha\_0 and declination \delta\_0. The two nodes of the body’s equator on the ICRF equator are at \alpha\_0\pm90^{\circ}. In Fig. 1, the node Q is defined as the node at \alpha\_0 + 90^{\circ}. The prime meridian is defined so that it crosses the body’s equator at the point B. The location of B is determined by the value for W, the angle measured _easterly_ along the body’s equator from the Q to B. The inclination of the planet’s equator to the celestial equator is 90^{\circ} − \delta\_0 . As long as the planet rotates uniformly, W varies nearly linearly with time. The parameters \alpha\_0, \delta\_0, and W may vary with time due to a precession of the axis of rotation of the planet or satellite. If W increases with time, the planet has a _direct_ (or prograde) rotation, and, if W decreases with time, the rotation is said to be _retrograde_. Can’t say that is crystal clear, but it is exactly what I (and everyone else) said. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [March 26, 2024, 11:45pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/27 "2024-03-26T23:45:16Z")
Astronomers define a planet’s “positive pole” (which on Earth is the same as the north pole) using the right-hand rule. Thumb is the positive pole, fingers curl in the direction of spin. So from the perspective of a body’s positive pole, they _all_ spin counter-clockwise. But from the perspective of the positive pole of Earth, or the sun, or the solar system as a whole (which all have the positive pole lined up with what we call north), some planets spin clockwise. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [March 27, 2024, 2:25am UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/28 "2024-03-27T02:25:44Z")
> [@Chronos](#): > > But you’re coiling it from above, which adds the needed asymmetry. Yes, obviously I was looking down on the coil of rope, so I assumed the coil was to be laid clockwise from my vantage point. What I couldn’t figure out was why the act of coiling the rope should twist the fibers in one direcction more than the other. Is that subject to the same asymmetry as my viewing position? Suppose I were to coil a rope in such a way that with each new loop I lifted the existing coils and slid the new one underneath. I’d be creating coils from the top down, instead of from the bottom up, so would that be clockwise or counter-clockwise? Years later I learned the technique for coiling electrical cables with alternating over and under loops. And because every thread needs a theme song. [https://www.youtube.com/watch?v=CvCjCsr\_Uw8](https://www.youtube.com/watch?v=CvCjCsr_Uw8) ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [March 27, 2024, 11:48am UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/29 "2024-03-27T11:48:35Z")
In the course of the typical coiling process, during the act of forming a loop, you’re putting a circumferential torque on the rope. Said another way, that’s equivalent to holding one end fixed and clamping the other end in a drill motor and spinning the far end once per coil loop formed. Clearly that could wreak havoc on a length of twisted rope if the motor was run in the direction opposite to the twist. Which is why both braided ropes were invented, as well as the various ways to coil hoses and electrical cords that avoid applying that twisting motion. Reels also solve this problem. So the issue _isn’t_ the resulting coil on the deck, which as you say _looks_ clockwise from above and equally counterclockwise from below. The issue is the 3D twisting you did as you created that coil. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 27, 2024, 12:50pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/30 "2024-03-27T12:50:35Z")
> [@LSLGuy](#): > > Quite right. Which is why astronomers have an extra special convention for Uranus. A whole convention, dedicated entirely to Uranus? Just what the hell makes you think everyone is so interested in Uranus? Sounds like a classic delusion of grandeur. You’re probably imagining standing on a stage with an entire arena of fans screaming “show us Uranus!” ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [March 27, 2024, 2:13pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/31 "2024-03-27T14:13:23Z")
> [@LSLGuy](#): > > Clearly that could wreak havoc on a length of twisted rope if the motor was run in the direction opposite to the twist. Is the problem with twisting the rope too much, or too little? I got the impression that the ropes were already twisted pretty tightly when they were created. If the act of coiling them increased the twist, that could overstress and break some of the natural fibers in the rope. If you coil the rope in such a way that it relaxes the natural twist, that would preserve the strength. Coiling a rope introduces a twist to it. When the rope is taken off the belaying pin, and the rope is used (to raise a sail, or whatever) does that counteract the coiling, or is the twisting cumulative each time the rope is coiled? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [March 30, 2024, 10:53pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/32 "2024-03-30T22:53:12Z")
If it’s uncoiled the same way that it’s coiled, then the net effect is zero. But you could get a cumulative effect if something is wound onto a rotating spool, but then looped off, or vice-versa. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [March 30, 2024, 11:14pm UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/33 "2024-03-30T23:14:56Z")
> [@Thudlow\_Boink](#): > > > [@pjd](#): > > > > I would interpret it as viewing from the top (N pole) > > But which is the top (or north), and why? I think because of analogy with the earth, where it’s clear by definition where “north” is, and the fact that all the other planets orbit in approximately the same orbital plane as earth, with various degrees of axial inclination. This is highlighted by the fact that Uranus rotates on its side, with an approximately 90° inclination, and most of us would be hard-pressed to say whether it rotates “clockwise” or “counterclockwise”. But for earth and the other planets, looking at the solar system “from the top” I think is the accepted convention. ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [April 1, 2024, 1:48am UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/34 "2024-04-01T01:48:12Z")
Even without knowing any of the information above, the fact that the question asks “which two” spin clockwise would tell me that you want the two which which, from the same perspective, rotate in the opposite direction of the six others. That said, I would in fact assume it meant the side of the orbital plane closest to Earth north. But that only works with reference to a single star that has the planets orbiting in the same general plane. I would not know what it would mean if you had a planet in a near perpendicular orbit relative to another. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [April 2, 2024, 3:06am UTC](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397/35 "2024-04-02T03:06:08Z")
> [@Chronos](#): > > If it’s uncoiled the same way that it’s coiled, then the net effect is zero. But you could get a cumulative effect if something is wound onto a rotating spool, but then looped off, or vice-versa. We would just lift the coil of rope off the pin and drop it on the deck. Then we’d raise or lower the sail (or whatever that line was connected to), then coil the loose end of the rope and hang it back up. I don’t know if that added a cumulative twist to the rope fibers or not. [Previous page](https://boards.straightdope.com/t/whats-your-interpretation-of-a-sphere-spinning-clockwise/999397.md?page=1)