Results 1 to 25 of 25

Thread: Can planets reverse their rotation direction?

  1. #1
    Join Date
    Jan 2004
    Posts
    5

    Can planets reverse their rotation direction?

    If so, is it known why this would occur?
    I do apologise if this is a horrifically stupid question, but someone was telling me (not with any scientific relevance... actually with esoteric/catastrophic implications :roll about this recently, and it doesn't make much sense to me. There's apparently a biblical reference that confirms that this has happened in earth's history... which only leaves me that much more skeptical. Help me not be a misinformed dumbass.

    Thanks!

  2. #2
    Join Date
    May 2003
    Posts
    1,035
    Not by themselves, no.

    For this to happen, some other planetary body would have to pass in very close proximity to the Earth, and in such a case, tidal forces would create geological evidence for us to see. We're finding such evidence relating to the Moon's orbital motions, and this is what we use to determine how far away the Moon has been in the past. Incidentally, a planet passing near the Earth would wreak havoc with the Moon's orbit.

  3. #3
    Join Date
    Oct 2001
    Posts
    7,817
    If your friend was refering to the battle of Jericho, where "the Sun stood still", this is physically impossible. The rotating Earth has tremendous kinetic energy. If it were to stop suddenly, all that kinetic energy would be converted to heat. The crust and mantle would be reduced to a molten state and the planet would be sterilized of all life.

  4. #4
    Join Date
    Sep 2003
    Posts
    1,484
    Quote Originally Posted by Kaptain K
    If your friend was refering to the battle of Jericho, where "the Sun stood still", this is physically impossible. The rotating Earth has tremendous kinetic energy. If it were to stop suddenly, all that kinetic energy would be converted to heat. The crust and mantle would be reduced to a molten state and the planet would be sterilized of all life.
    How long is it supposed to have stood still for?

  5. #5
    Join Date
    Apr 2003
    Posts
    992
    Did anyone named Nancy come up in the conversation?

  6. #6
    Join Date
    May 2002
    Posts
    2,046

    Re: Can planets reverse their rotation direction?

    Quote Originally Posted by Psychotron
    If so, is it known why this would occur?
    There's apparently a biblical reference that confirms that this has happened in earth's history... which only leaves me that much more skeptical. Help me not be a misinformed dumbass.
    Well, in the case of the Bible, you are talking about the Supreme Being who created the Heavens and the Earth and all they contain. If He, the Author of life, decided to grab the world and spin it backwards for a bit or hold it still, and manipulate things such that gravity problems would not occur - who is to say He cannot? He made the rules, He can bend them a bit for His purposes.

    Basically, something like that could only happen through a divine miracle. If a person believes in the spiritual realm, than with what we know, only a spriritual realm explanation can suffice for this.

    Scientifically and naturally speaking though, no it could not happen.

    See the difference?

  7. #7
    Join Date
    Apr 2003
    Posts
    835

    Re: Can planets reverse their rotation direction?

    Quote Originally Posted by Psychotron
    If so, is it known why this would occur?
    I do apologise if this is a horrifically stupid question, but someone was telling me (not with any scientific relevance... actually with esoteric/catastrophic implications :roll about this recently, and it doesn't make much sense to me. There's apparently a biblical reference that confirms that this has happened in earth's history... which only leaves me that much more skeptical. Help me not be a misinformed dumbass.

    Thanks!
    Yeah, but it's a real pain working a gear shifter two hundred miles tall.

  8. #8
    Join Date
    Feb 2003
    Posts
    293
    Venus rotates clockwise around its axis when viewed from its north pole and is the only planet in the solar system with such a rotation. It also rotates extremely slowly, taking 243 Earth days for one axial rotation. One theory is that it was struck by another object that reversed its rotation. Another is that solar tidal forces slowly reversed it. This in no way relates to legends of Earth orbit reversal. Moreover, in Biblical days they didn't even know the Earth rotated about an axis.

  9. #9
    Join Date
    Oct 2002
    Posts
    1,860
    Quote Originally Posted by Ian Goddard
    Venus rotates clockwise around its axis when viewed from its north pole and is the only planet in the solar system with such a rotation.
    Neptune is inclined at 97 degrees, which makes its rotation slightly retrograde. Pluto is inclined at 122 degrees, but maybe you don't consider Pluto a planet.

  10. #10
    Join Date
    Oct 2001
    Posts
    7,817
    Quote Originally Posted by daver
    Quote Originally Posted by Ian Goddard
    Venus rotates clockwise around its axis when viewed from its north pole and is the only planet in the solar system with such a rotation.
    Neptune is inclined at 97 degrees, which makes its rotation slightly retrograde. Pluto is inclined at 122 degrees, but maybe you don't consider Pluto a planet.
    Uranus 8)

  11. #11
    Join Date
    Feb 2003
    Posts
    293
    Quote Originally Posted by daver
    Quote Originally Posted by Ian Goddard
    Venus rotates clockwise around its axis when viewed from its north pole and is the only planet in the solar system with such a rotation.
    Neptune is inclined at 97 degrees, which makes its rotation slightly retrograde. Pluto is inclined at 122 degrees, but maybe you don't consider Pluto a planet.
    Yeah, I guess for Uranus and Pluto it depends on what we define as "north pole." Looking into this quickly, some sources say Venus is unique as I noted, but one source I found agrees with your point (albeit for Uranus (not Neptune) and Pluto).

  12. #12
    Join Date
    Oct 2001
    Location
    Sioux Falls, SD
    Posts
    7,960
    Quote Originally Posted by Ian Goddard
    Yeah, I guess for Uranus and Pluto it depends on what we define as "north pole."
    Wouldn't you guess that for any planet it depends on what we define as "north pole"?

  13. #13
    Join Date
    Oct 2001
    Posts
    2,442
    Can planets reverse their rotation direction?

    Yes & no. The angular momentum vector for the planet (the line that passes through both the north & south poles) cannot change its orientation in space by mechanisms purely internal to the planet. An outside force is required. Note that, in this case, the atmosphere is an "outside" force.

    The strong tilt of Uranus that has the planet laying dowm on it's side was most likely caused by a very large impact, early in the planet formation process (see, for instance, Planet Formation, J.J. Lissauer, Annual Review of Astronomy and Astrophysics, 31: 129-174, 1993).

    The rotation of Venus is , on the other hand, only barely retrograde. It could be explained by a similar but smaller collision, but the small nature of the effect allows for other, even better explanations. Exchange of angular momentum between the planet and its atmosphere, through thermal or solar tides, could push its spin axis over by the small observed amount (i.e., Evolution of the Spin of Venus, J. McCue & j.R. Dormand, Earth Moon and Planets, 63(3): 209-225, December 1993). Or, it could simply be a result of natural "chaos" in the solar system, where planets without moons can "quickly" change obliquity due to the combined torques of the other planets (i.e., Venus' Free Obliquity, C.F. Yoder, Icarus 117(2): 250-286, October 1995; The Chaotic Obliquity of the Planets, J. Laskar & P. Robutel, Nature 361(6413): 608-612, February 18, 1993). But the obliquity of Earth is stabilized by the presence of our moon (Stabilization of Earth's Obliquity by the Moon, J. Laskar, F. Joutel & P. Robutel, Nature 361(6413): 615-617, February 18, 1993) so that won't happen here.

    There is another effect, called true polar wander. It is a consequence of the fact that the planets are not rigid bodies, but have fluid interiors. The redistribution of mass by internal fluid flow changes the moment of inertia of the planet, and therefore changes the orientation of the planet with respect to its spin axis. In that case, even while the spin axis remains fixed in space, the planet can still roll over. An observer on the planet would see the spin axis (the location of the poles) change with time, with respect to the "fixed" surface of the planet. Hence the term "polar wander", as we see the poles wander about the surface. In 1997 a team from Caltech made the news by asserting that true polar wander was a key feature in changing early climate on Earth (Cambrian True Polar Wander). The current manifestation of polar wander is a cyclic motion of the pole called Chandler Wobble. Rigid bodies can undergo polar wnder, but it will be an invariant oscillation. Bodies with fluid interiors, like planets, can undergo variable wander.

    So, if you think that atmospheric torque or internal mass redistribution amount to a planet "self reversing", than yes, planets can change their own spin, within limits. But the big stuff, like Uranus' obliquity, require major outside interference.

  14. #14
    Join Date
    Feb 2003
    Posts
    293
    Quote Originally Posted by SeanF
    Quote Originally Posted by Ian Goddard
    Yeah, I guess for Uranus and Pluto it depends on what we define as "north pole."
    Wouldn't you guess that for any planet it depends on what we define as "north pole"?
    Well, the "north pole" of a planet is derived from a standard applied to the solar system as a whole. That's why things seem to get arbitrary when a planet, like Uranus, has its axis pointed toward the Sun... I guess then it's the East or West pole. :-?

  15. #15
    Join Date
    Feb 2003
    Posts
    293
    Thanks Tim. The question remains: is Pluto's motion retrograde? If that's what daver implies, and one of the following sources seems to agree. Here's what I have from two sources:

    "All the planets revolve about the Sun in the same sense. When the rotation of the planet is also in this direction we speak of direct rotation. In the opposite case the rotation is termed retrograde. Among the planets, Venus and Uranus have retrograde motions." (Audouze, Jean & Guy Israel. The Cambridge Atlas of Astronomy. Cambridge UP, 1988: 53.) Does that mean only Venus and Uranus?

    The rotation of Venus "takes place in the direction opposite that of the rotation of the Earth and of all the other planets except Uranus and Pluto." (Goldsmith, Donald & Tobias Owen. The Search for Life in the Universe. 3rd ed. Sausalito, CA: University Science Books, 2001: 292-3.)

    Here's a source that makes the error I did in excluding (at least) Uranus:

    "One other interesting note is that Venus rotates clockwise, the only planet in our solar system to do so, and contrary to its own orbit around the Sun." Venus, National Weather Service.

  16. #16
    Join Date
    Oct 2002
    Posts
    1,860
    Quote Originally Posted by Kaptain K
    Uranus 8)
    ops:

  17. #17
    Join Date
    Oct 2001
    Posts
    2,442
    I think Pluto's motion is retrograde. See Obliquity of the Nine Planets and the associated jpeg image. Although, I think the obliquity of Pluto is now thought to be a bit larger, about 124 degrees, compared to Calvin Hamilton's 119 degrees. It is actually quite difficult to get at Pluto's rotation, since only the HST images show any details on the surface to use as rotation markers.

  18. #18
    Join Date
    Oct 2001
    Posts
    1,252
    Quote Originally Posted by Tim Thompson
    So, if you think that atmospheric torque or internal mass redistribution amount to a planet "self reversing", than yes, planets can change their own spin, within limits. But the big stuff, like Uranus' obliquity, require major outside interference.
    even so, wouldn't it be safe to assume that such changes would likely take eons to occur?

    mark

  19. #19
    Join Date
    Oct 2001
    Posts
    2,442
    I'm not sure what an "eon" amounts to. In the Cambrian true polar wander paper that I linked to earlier, by Kirschvink et al., their entire episode of polar wander took about 17,000,000 years. That would look pretty slow to anybody on the planet, but it pretty quick by geological standards. Likwise, the mobility of the obliquity of unstabilized Venus is still such that it takes, at its quickest, "a few million years" to change obliquity by 50 degrees. Again, that looks slow to a surface bound observer, but is really fast by geological standards. So i think it's safe to say "millions of years" is how long this kind of stuff takes.

  20. #20
    Join Date
    Jan 2002
    Posts
    922

    Re: Can planets reverse their rotation direction?

    Quote Originally Posted by nebularain
    Quote Originally Posted by Psychotron
    If so, is it known why this would occur?
    There's apparently a biblical reference that confirms that this has happened in earth's history... which only leaves me that much more skeptical. Help me not be a misinformed dumbass.
    Well, in the case of the Bible, you are talking about the Supreme Being who created the Heavens and the Earth and all they contain. If He, the Author of life, decided to grab the world and spin it backwards for a bit or hold it still, and manipulate things such that gravity problems would not occur - who is to say He cannot? He made the rules, He can bend them a bit for His purposes.
    Quote Originally Posted by Kaptain K
    If your friend was refering to the battle of Jericho, where "the Sun stood still", this is physically impossible...
    I agree with Nebularain.
    God seems to specialize in the 'physically impossible'. I guess that's part of what makes Him God.

    By the way, it wasn't at the Battle of Jericho. It was during Joshua's Battle against the Amorites in Gibeon & Bethhoren. :wink: (See Joshua 10:12-13)

    G^2

  21. #21
    Join Date
    Jun 2003
    Posts
    55
    If a pole shift were to occur over 90 degrees then the sun would set east instead of west without changing directional spin.Hold a ball and slowly turn it then lean the top pole past the equator line and you will see this effect.

  22. #22
    Join Date
    Jun 2003
    Posts
    460
    Quote Originally Posted by Tim Thompson
    I'm not sure what an "eon" amounts to. In the Cambrian true polar wander paper that I linked to earlier, by Kirschvink et al., their entire episode of polar wander took about 17,000,000 years. That would look pretty slow to anybody on the planet, but it pretty quick by geological standards. Likwise, the mobility of the obliquity of unstabilized Venus is still such that it takes, at its quickest, "a few million years" to change obliquity by 50 degrees. Again, that looks slow to a surface bound observer, but is really fast by geological standards. So i think it's safe to say "millions of years" is how long this kind of stuff takes.
    Such as during a period of massive flood vulcanism?

  23. #23
    Join Date
    Dec 2003
    Posts
    55
    Quote Originally Posted by Tim Thompson
    I think Pluto's motion is retrograde. See Obliquity of the Nine Planets and the associated jpeg image.
    In that jpeg image, it says Venus's obliquity is 177 degrees, yet it clearly looks, in the image, as if it is almost 360 degrees. I don't get it...

  24. #24
    Join Date
    Oct 2001
    Posts
    29,218
    Quote Originally Posted by Lorcan Faol
    Quote Originally Posted by Tim Thompson
    I think Pluto's motion is retrograde. See Obliquity of the Nine Planets and the associated jpeg image.
    In that jpeg image, it says Venus's obliquity is 177 degrees, yet it clearly looks, in the image, as if it is almost 360 degrees. I don't get it...
    Look closely at the arrow indicating the direction of rotation - it's going the other way from the other planets.
    Everything I need to know I learned through Googling.

  25. #25
    Join Date
    Dec 2003
    Posts
    55
    Quote Originally Posted by ToSeek
    Quote Originally Posted by Lorcan Faol
    Quote Originally Posted by Tim Thompson
    I think Pluto's motion is retrograde. See Obliquity of the Nine Planets and the associated jpeg image.
    In that jpeg image, it says Venus's obliquity is 177 degrees, yet it clearly looks, in the image, as if it is almost 360 degrees. I don't get it...
    Look closely at the arrow indicating the direction of rotation - it's going the other way from the other planets.

    ahhh, alright. Gotcha. 8)

Similar Threads

  1. Direction of rotation.???
    By P Timmy in forum Science and Technology
    Replies: 25
    Last Post: 2012-May-01, 11:24 AM
  2. rotation speed of planets
    By Hekate's Lair in forum Astronomy
    Replies: 3
    Last Post: 2008-Mar-26, 12:43 PM
  3. What makes all the planets orbit the Sun in the same direction?
    By jgreen1124 in forum Space/Astronomy Questions and Answers
    Replies: 7
    Last Post: 2007-Oct-06, 01:39 PM
  4. Why do all planets orbit in the same direction?
    By The_Radiation_Specialist in forum Space/Astronomy Questions and Answers
    Replies: 23
    Last Post: 2006-Apr-01, 04:02 AM
  5. Planets Running in Reverse
    By Fraser in forum Universe Today
    Replies: 4
    Last Post: 2006-Feb-16, 02:57 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
here
The forum is sponsored in-part by: