<P> The Moon has a stabilizing effect on Earth's obliquity . Frequency map analysis conducted in 1993 suggested that, in the absence of the Moon, the obliquity can change rapidly due to orbital resonances and chaotic behavior of the Solar System, reaching as high as 90 ° in as little as a few million years (also see Orbit of the Moon). However, more recent numerical simulations made in 2011 indicated that even in the absence of the Moon, Earth's obliquity might not be quite so unstable; varying only by about 20--25 ° . The Moon's stabilizing effect will continue for less than 2 billion years . If the Moon continues to recede from Earth due to tidal acceleration, resonances may occur which will cause large oscillations of the obliquity . </P> <P> All four of the innermost, rocky planets of the Solar System may have had large variations of their obliquity in the past . Like Earth, all of the rocky planets have a small precessional rotation of their spin axis . This rate varies due to, among other things, tidal dissipation and core - mantle interaction . When each planet reaches certain values of precession, orbital resonances may cause very large, chaotic changes in obliquity. Mercury and Venus have most likely been stabilized by the tidal dissipation of the Sun . Earth was stabilized by the Moon, as above, but before its capture, Earth, too, could have passed through times of instability . Mars's obliquity is currently in a chaotic state; it varies as much as 0 ° to 60 ° over some millions of years, depending on perturbations of the planets . The obliquities of the outer planets are considered relatively stable . Some authors dispute that Mars's obliquity is chaotic, and show that tidal dissipation and viscous core - mantle coupling are adequate for it to have reached a fully damped state, similar to Mercury and Venus . </P> <Table> Axis and rotation of selected Solar System bodies <Tr> <Th> Body </Th> <Th_colspan="4"> NASA, J2000. 0 </Th> <Th_colspan="4"> IAU, 0 Jan 2010, 0h TT </Th> </Tr> <Tr> <Th> Axial tilt (degrees) </Th> <Th_colspan="2"> North Pole </Th> <Th> Rotation (hours) </Th> <Th> Axial tilt (degrees) </Th> <Th_colspan="2"> North Pole </Th> <Th> Rotation (deg / day) </Th> </Tr> <Tr> <Th> R.A. (degrees) </Th> <Th> Dec. (degrees) </Th> <Th> R.A. (degrees) </Th> <Th> Dec. (degrees) </Th> </Tr> <Tr> <Td> Sun </Td> <Td> 7.25 </Td> <Td> 286.13 </Td> <Td> 63.87 </Td> <Td> 609.12 </Td> <Td> 7.25 </Td> <Td> 286.15 </Td> <Td> 63.89 </Td> <Td> 14.18 </Td> </Tr> <Tr> <Td> Mercury </Td> <Td> 0.03 </Td> <Td> 281.01 </Td> <Td> 61.42 </Td> <Td> 1407.6 </Td> <Td> 0.01 </Td> <Td> 281.01 </Td> <Td> 61.45 </Td> <Td> 6.14 </Td> </Tr> <Tr> <Td> Venus </Td> <Td> 2.64 </Td> <Td> 272.76 </Td> <Td> 67.16 </Td> <Td>--5832.6 </Td> <Td> 2.64 </Td> <Td> 272.76 </Td> <Td> 67.16 </Td> <Td> − 1.48 </Td> </Tr> <Tr> <Td> Earth </Td> <Td> 23.44 </Td> <Td> 0.00 </Td> <Td> 90.00 </Td> <Td> 23.93 </Td> <Td> 23.4 </Td> <Td> undef . </Td> <Td> 90.00 </Td> <Td> 360.99 </Td> </Tr> <Tr> <Td> Moon </Td> <Td> 6.68 </Td> <Td>--</Td> <Td>--</Td> <Td> 655.73 </Td> <Td> 1.54 </Td> <Td> 270.00 </Td> <Td> 66.54 </Td> <Td> 13.18 </Td> </Tr> <Tr> <Td> Mars </Td> <Td> 25.19 </Td> <Td> 317.68 </Td> <Td> 52.89 </Td> <Td> 24.62 </Td> <Td> 25.19 </Td> <Td> 317.67 </Td> <Td> 52.88 </Td> <Td> 350.89 </Td> </Tr> <Tr> <Td> Jupiter </Td> <Td> 3.13 </Td> <Td> 268.05 </Td> <Td> 64.49 </Td> <Td> 9.93 </Td> <Td> 3.12 </Td> <Td> 268.06 </Td> <Td> 64.50 </Td> <Td> 870.54 </Td> </Tr> <Tr> <Td> Saturn </Td> <Td> 26.73 </Td> <Td> 40.60 </Td> <Td> 83.54 </Td> <Td> 10.66 </Td> <Td> 26.73 </Td> <Td> 40.59 </Td> <Td> 83.54 </Td> <Td> 810.79 </Td> </Tr> <Tr> <Td> Uranus </Td> <Td> 82.23 </Td> <Td> 257.43 </Td> <Td>--15.10 </Td> <Td>--17.24 </Td> <Td> 82.23 </Td> <Td> 257.31 </Td> <Td> − 15.18 </Td> <Td> − 501.16 </Td> </Tr> <Tr> <Td> Neptune </Td> <Td> 28.32 </Td> <Td> 299.36 </Td> <Td> 43.46 </Td> <Td> 16.11 </Td> <Td> 28.33 </Td> <Td> 299.40 </Td> <Td> 42.95 </Td> <Td> 536.31 </Td> </Tr> <Tr> <Td> Pluto </Td> <Td> 57.47 </Td> <Td> (312.99) </Td> <Td> (6.16) </Td> <Td>--153.29 </Td> <Td> 60.41 </Td> <Td> 312.99 </Td> <Td> 6.16 </Td> <Td> − 56.36 </Td> </Tr> <Tr> <Th_colspan="9"> with respect to the ecliptic of 1850 at 16 ° latitude; the Sun's rotation varies with latitude with respect to the ecliptic; the Moon's orbit is inclined 5.16 ° to the ecliptic from the origin of the radio emissions; the visible clouds generally rotate at different rate NASA lists the coordinates of Pluto's positive pole; values in (parentheses) have been reinterpreted to correspond to the north / negative pole . </Th> </Tr> </Table> <Tr> <Th> Body </Th> <Th_colspan="4"> NASA, J2000. 0 </Th> <Th_colspan="4"> IAU, 0 Jan 2010, 0h TT </Th> </Tr>

When does the earth move most rapidly in its orbit