# Astroquizzical: Do all planets rotate in orbit around their stars? (Synopsis)

When you think about our world and our place in the Solar System, you very likely think about Earth, spinning on its axis, with the Moon orbiting around it, and with the entire Earth-Moon system orbiting the Sun.

But did you know that all of it -- the Earth spinning on its axis, the Moon revolving around Earth, the Earth revolving around the Sun, and even the Sun spinning on its own axis -- spins in the same direction? If you floated "above" the north pole of Earth, everything would rotate counterclockwise. It makes you wonder, as one of Jillian Scudder's questioners did:

Do all planets rotate as they go around their stars? Do they all rotate in the same direction (e.g. clockwise or anticlockwise?) Or does it just depend on what started them rotating in the first place?

Image credit: Calvin J. Hamilton.
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If we had a bird’s eye view of our solar system, where we’d flown into space “up” via the North Pole, and looked back down, most of the planets would be rotating counterclockwise — or from the West towards the East.

What defines North/South and East/West here? If Venus rotates in the opposite direction to Earth, would we say that there the sun rises in the West and sets in the East? Or do we define the poles by the direction of rotation, so that Venus' North Pole points the other way than Earth's?

@Morgan #1: In the quote from Ms. Scudder (Ethan's guest author) above, she defines North based on the Earth ("[fly] into space 'up' via the North Pole"). It turns out that, for our solar system, that definition displays "clockwise" rotation for not just Earth, but for a majority of the planets and for the Sun. It also displays clockwise revolution for all the planets in orbit.

For other planets (in the solar system), we define the poles such that the local "north" pole is the one with clockwise rotation (i.e., the Sun always rises in local east, except on Uranus where it rises in the north, I think :-) ).

By Michael Kelsey (not verified) on 31 Mar 2015 #permalink

Another thing: the earth technically does not orbit the sun. The earth and the sun orbit each other around their center of mass. It is only due to the enormous difference in mass of the sun and the earth that we accept that the center of mass is the center off the sun.
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By Cherise Swanepoel (not verified) on 31 Mar 2015 #permalink

Truly something to think about. If you for instance float above another planet, say Saturn, would it then look like the planets are turning in a different direction then when you are floating "above" the earth's north pole?
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By Michaela van Rooyen (not verified) on 31 Mar 2015 #permalink

Michael,

I would think it's actually impossible for the rotation of the earth as seen from above the north pole to be anything other than "clockwise". We make clock hands go clockwise precisely because that it the direction that the shadow in a sundial moves. It moves in that direction because of the direction of the earth's rotation. If the earth rotated in the opposite sense, we would define the direction we now refer to as "counterclockwise" as being "clockwise" instead.

Of course, the main point that the rotational sense of most objects in the universe remains, despite how we define our term "clockwise".

I enjoy thinking of the ecliptic as a "fossil" reflection of our system's accretion disc.

Migrating gas giants would introduce enough gravitational turbulence to produce planetary billiards - a mechanism to knock a planet on it's ear.

In the time-lapse of the Sun above, I would really like to understand the nature of the banding seen on each side of the Sun's equator where solar flairs tend to manifest.
Is the mechanism driven by temperature or magnetism?

Similar banding is displayed in the weather on Earth which I believe is a function of temperature, and of course on Jupiter where it's fantastic speed of rotation probably factors in...?

By David Andrews (not verified) on 31 Mar 2015 #permalink

I enjoy thinking of the ecliptic as a "fossil" reflection of our system's accretion disc.

Migrating gas giants would introduce enough gravitational turbulence to produce planetary billiards - a mechanism to knock a planet on it's ear.

In the time-lapse of the Sun above, I would really like to understand the nature of the banding seen on each side of the Sun's equator where solar flares tend to manifest.
Is the mechanism driven by temperature or magnetism?

Similar banding is displayed in the weather on Earth which I believe is a function of temperature, and of course on Jupiter where it's fantastic speed of rotation probably factors in...?

By David Andrews (not verified) on 31 Mar 2015 #permalink

@#2 Mr Kelsey. Ms Scudders definition is correct, as in we rotate counterclockwise viewed from 'north'. Uranus lies on its side (+98, or -82 degrees), therefore the sun remains facing its (respective) pole for approx. 42 years.

I read an article a few months ago which made what seemed like a good case that Venus' rotation was explained, not by a late impact, but by orbital resonance with the sun, modified slightly by the effects of the planet's thick atmosphere. ("Seemed" because I don't have enough math to check the work.)

And now I wish I'd bookmarked that, but I didn't think I'd want it again, and I don't remember what series of links or questions got me there. Ethan? Gillian? Does this sound at all familiar?

@#5, SeanT
The shadow upon the sun dial moves left to right (clockwise) simply because the sun moves east to west simply because the earth rotates anticlockwise looking from above the north pole. I think you will find clocks were designed this way for this simple reason of the shadow moving in a 'clockwise' motion.

What defines North/South and East/West here?

The British Empire. Just like the definition of the meridian line.

From the UK, the pole is "up" from the sun at our temperate latitude so we do our maps that way round. And since we spent a long time being masters of the sea with a huge empire, our colonies used the same maps as did our allies against France and Spain. Since those two lost their empires, and France was more a land power anyway, the British system became universal. For all the other powers it was still fine to have the same North since the sun did the same dance for them.

If Australasia had did the conquering, we'd have North at the other end.

Agreed, PJ. That was kind of my point. If the earth rotated in the opposite sense, then sundial shadows would move in the opposite direction. Clocks would likely have been designed to move in that direction, and the opposite rotational sense would now be referred to as "clockwise".

It is not possible for the earth's rotation as seen from above the north pole to be anything but clockwise. That rotational sense is what defines the term "clockwise".

Say that research tells us that all the planets do rotate or spin in the same direction. What would cause all the planets, of different sizes, to rotate this way?

By Megan (u15031153) (not verified) on 01 Apr 2015 #permalink

The Earth rotates from the west towards the east, as viewed from the North Star or polestar Polaris and the Earth turns counter-clockwise. It is true that the earth does not just orbit the sun, but they both orbit due to their centre of mass. The rotation of the earth gives night and day however, is it possible for some planets to rotate without it having the effect of night and day, as on earth, due to its difference in size? Do other planets for example Neptune, also experience different seasons even though they may be very far from the sun? Thank you for your time! u15007473

Certain research states a theory that if the earth rotation axis slows down, it would result in the Earth's gravity depleting, is it true that rotation axis of the earth plays an important variable in stabilizing gravitational force on earth?

By Joshua Ndoli(u… (not verified) on 02 Apr 2015 #permalink

It makes sense that a collision or collisions could have caused that Uranus is rotating on its side, but wouldn't there be some kind of evidence because of the great impact to cause this? 15057357

By T. Duvenage (not verified) on 02 Apr 2015 #permalink

What would cause all the planets, of different sizes, to rotate this way?

Conservation of angular momentum. The accretion disk at the outside edge has to fall in to the galactic centre, speeding up and that on the inside edge move outward, slowing down.

And then the accretion of stars and planets have the same issue within that rotating accretion disk.

I'm curious... what's with the recent influx of commenters from South Africa signing their comments with an 8-digit number and sometimes a 'u'? Is it some kind of school or university ID?

By darkgently (not verified) on 02 Apr 2015 #permalink

It may be the result of people posting from medium.com and an account on it.

One thing to keep in mind is that the Sun an the planets around it share a relative gravitational field with each other. The centre of gravity is then focused on the sun and this basically makes all the planets including asteroids rotate in the same direction
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One last question in reference to the angle of axis does it influence the gravitational force upon the planet...e.g greater the angle of axis ,greater the gravity?

I have been researching on the topic but I am not getting accurate information! Just long explanations without accurate results.

By Joshua Ndoli (… (not verified) on 03 Apr 2015 #permalink

Ndoli #21: No, the rotational inclination doesn't affect a planet's gravity.

By Michael Kelsey (not verified) on 03 Apr 2015 #permalink

The Nebula Hypothesis explained extensively.The movements of the planets makes a lot of sense when you consider that they should follow the direction of the innermost(Sun). I have also followed on the two great collisions that changed the movements of Venus and Uranus,and I think although there is not much conviction from the astrophysicists' theories,I find it sensible to conclude that indeed these collisions did occur.
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By Ntokozo Dlamini (not verified) on 03 Apr 2015 #permalink

@Ntokozo Dlamini:
Do these planets rotate in the same direction?if they do, do they rotate in the same direction when following the Nebula Hypothesis?

By Mashaba FS-u13356004 (not verified) on 05 Apr 2015 #permalink

It is the first time a heard about nebula hypothesis and it makes a sense to me. In the time-lapse of the Sun above, I would really like to understand the nature of the banding seen on each side of the Sun’s equator where solar flares tend to manifest.
Is the mechanism driven by temperature or magnetism?

By jacobus du ple… (not verified) on 05 Apr 2015 #permalink

@ Mashaba they do rotate in the same direction actually most of these planets in this Solar System rotate in the same direction almost like as they orbit the Sun, which is as you know counter-clockwise as seen from above the Sun's north pole, but the the exceptions i know of are Venus and Uranus, which rotate clockwise, though Uranus's extreme axial tilt means there are differing conventions on which of its poles is "north", and therefore whether it is rotating clockwise or anti-clockwise .but i do believe they follow the Nebula Hypothesis ....

By Kevin RK u14169046 (not verified) on 05 Apr 2015 #permalink

Does it really matter if the planets do rotate in the same direction? What gets affected by the direction of the rotation?

By u15162258 (not verified) on 06 Apr 2015 #permalink

#27 it is important that all the planets rotate in the same plane in order for them to be classified as bodies from our solar system. A perfect example is Pluto, which is no longer part of our solar system mainly because it did not orbit in the same plane as the other planets, hence dwarf planets.

what makes the spinning of the earth on its axis and all the things that revolve on it to spin in the same direction and if there were to spin in different direction how would that change the whole universe we know today?
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By sendra kawa (not verified) on 13 Apr 2015 #permalink