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27:
102:. That is similar to a brick rotating around an axis going through its shortest dimension (a vertical axis when the brick is lying flat). However, if the moment of inertia around one of the two axes close to the equator becomes nearly equal to that around the polar axis, the constraint on the orientation of the object (the Earth) is relaxed.
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spinning around an axis running through its "equator". (Note that the "equator" of the ball does not correspond to the equator of the Earth.) Small perturbations can move the football, which then spins around another axis through the same "equator". In the same way, conditions can make the Earth
226:. To reconstruct plate tectonic histories, geologists must obtain a number of dated paleomagnetic samples. Because true polar wander is a global phenomenon but tectonic motions are specific to each plate, multiple dates allow them to separate the tectonic and true polar wander signals.
152:
is not an instance of true polar wander (a shift of the body relative to its rotational axis), but instead a large shift of the rotational axis itself. This axis shift is believed to be the result of a catastrophic series of impacts that occurred billions of years ago.
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If the body is near the steady state but with the angular momentum not exactly lined up with the largest moment of inertia axis, the pole position will oscillate. Weather and water movements can also induce small changes. These subjects are covered in the article
275:
Steinberger, Ross N.; Thissen, Christopher J.; Evans, David A. D.; Slotznick, Sarah P.; Coccioni, Rodolfo; Yamazaki, Toshitsugu; Kirschvink, Joseph L. (2008). "Absolute plate motions and true polar wander in the absence of hotspot tracks".
129:
Cases of true polar wander have occurred several times in the course of the Earth's history. It has been suggested that east Asia moved south due to true polar wander by 25° between about 174 and 157 million years ago.
165:, which is where the axis of rotation moves, in other words the North Pole points toward a different star. There are also smaller and faster variations in the axis of rotation going under the term
57:. If the body is not in this steady state, true polar wander will occur: the planet or moon will rotate as a rigid body to realign the largest moment of inertia axis with the spin axis. (See
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114:(both the crust and the mantle) slowly reorient until a new geographic point moves to the North Pole, with the axis of low moment of inertia being kept very near the equator.
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661:
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is greatest is closely aligned with the rotation axis (the axis going through the geographic North and South Poles). The other two axes are near the
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of most points on the Earth by an amount that depends on how far they are from the axis near the equator that does not move.
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to change, or "wander". Unless the body is totally rigid (which the Earth is not), its stable state rotation has the largest
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is a solid-body rotation of a planet or moon with respect to its spin axis, causing the geographic locations of the
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by finding the paleolatitude of a particular site. This paleolatitude is affected both by true polar wander and by
177:, and occurs all the time and at a much faster rate than polar wander. It does not result in changes of latitude.
184:, which is where different parts of the Earth's crust move in different directions because of circulation in the
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axis aligned with the spin axis, with the smaller two moments of inertia axes lying in the plane of the
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248:(includes discussion of various historical conjectures involving rapid shift of the poles)
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are also believed to have undergone true pole wander, in the case of Europa by 80°.
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386:"A true polar wander trigger for the Great Jurassic East Asian Aridification"
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The effect should further not be confused with the effect known as
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is not spherically symmetric, and the Earth has three different
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169:. Precession is caused by the gravitational attraction of the
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Reconstruction time at 540 Ma compared to paleomagnetism
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This diagram of true polar wander shows the present-day
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195:that describes the repeated proven reversal of the
329:"A Late Cretaceous true polar wander oscillation"
202:
156:
699:
180:True polar wander has to be distinguished from
327:Mitchell, Bernhard; Torsvik, Trond H. (2021).
662:Pacific–North American teleconnection pattern
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34:rotating with respect to its rotational axis
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148:' extreme inclination with respect to the
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161:Polar wander should not be confused with
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19:For broader coverage of this topic, see
16:Wandering of a planet's pole of rotation
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498:
607:Equatorial Indian Ocean oscillation
470:"Tipped Over By Several Collisions"
75:Description in the context of Earth
13:
384:Zhiyu Yi; et al. (Oct 2019).
206:
14:
729:
597:Diurnal air temperature variation
582:Cataclysmic pole shift hypothesis
567:Atlantic multidecadal oscillation
246:Cataclysmic pole shift hypothesis
117:Such a reorientation changes the
468:Kate Taylor (October 11, 2011).
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424:
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203:Tectonic plate reconstructions
157:Distinctions and delimitations
1:
262:
86:The mass distribution of the
602:El Niño–Southern Oscillation
94:. The axis around which the
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652:Pacific decadal oscillation
229:
218:is used to create tectonic
197:magnetic field of the Earth
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10:
734:
667:Quasi-biennial oscillation
637:North Atlantic oscillation
542:Antarctic Circumpolar Wave
431:Ron Cowen (June 7, 2008).
353:10.1038/s41467-021-23803-8
78:
59:Polhode § Description
18:
642:North Pacific Oscillation
622:Madden–Julian oscillation
532:
257:True polar wander on Mars
105:This situation is like a
587:Dansgaard–Oeschger event
562:Atlantic Equatorial mode
79:For magnetic poles, see
657:Pacific Meridional Mode
212:
35:
552:Arctic dipole anomaly
547:Antarctic oscillation
333:Nature Communications
236:Apparent polar wander
220:plate reconstructions
210:
29:
526:Climate oscillations
445:(18). Archived from
193:geomagnetic reversal
81:Geomagnetic reversal
627:Milankovitch cycles
617:Indian Ocean Dipole
480:on January 26, 2012
449:on November 4, 2011
402:2019Geo....47.1112Y
345:2021NatCo..12.3629M
298:10.1038/nature06824
290:2008Natur.452..620S
572:Earth's axial tilt
557:Arctic oscillation
213:
92:moments of inertia
36:
695:
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687:True polar wander
682:Solar variability
396:(12): 1112–1116.
284:(7187): 620–623.
182:continental drift
111:American football
96:moment of inertia
51:moment of inertia
39:True polar wander
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433:"A Shifty Moon"
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535:oscillations
484:February 29,
482:. Retrieved
478:the original
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451:. Retrieved
447:the original
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438:Science News
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252:Polar motion
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68:Polar motion
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21:Polar wander
713:Geodynamics
339:(1): 3629.
47:south poles
702:Categories
577:Bond event
263:References
241:Axial tilt
163:precession
418:210309183
140:Enceladus
119:latitudes
474:TG Daily
371:34131126
306:18385737
230:See also
167:nutation
150:ecliptic
125:Examples
708:Geodesy
677:Seasons
632:Monsoon
533:Climate
453:May 29,
398:Bibcode
390:Geology
362:8206135
341:Bibcode
314:4344501
286:Bibcode
100:equator
55:equator
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312:
304:
278:Nature
186:mantle
146:Uranus
138:, and
136:Europa
109:or an
414:S2CID
310:S2CID
88:Earth
43:north
32:Earth
486:2012
455:2008
367:PMID
302:PMID
173:and
171:Moon
132:Mars
45:and
443:173
406:doi
357:PMC
349:doi
294:doi
282:452
175:Sun
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
