Other Objects of The Solar System
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. The Earth was stabilized by the Moon, as above, but before its capture, the Earth, too, could have passed through times of instability. Mars' 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' 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.
| NASA, J2000.0 | IAU, 0 Jan 2010, 0h TT | |||||||
| Axial tilt | North Pole | Rotation | Axial tilt | North Pole | Rotation | |||
| ( ° ) | R.A. ( ° ) | Dec. ( ° ) | ( hours ) | ( ° ) | R.A. ( ° ) | Dec. ( ° ) | ( ° / day ) | |
| Sun | 7.25 | 286.13 | 63.87 | 609.12B | 7.25A | 286.15 | 63.89 | 14.18 |
| Mercury | ~0 | 281.01 | 61.45 | 1407.6 | 0.01 | 281.01 | 61.45 | 6.14 |
| VenusE | 177.36 | (92.76) | (-67.16) | (5832.5) | 2.64 | 272.76 | 67.16 | -1.48 |
| Earth | 23.4 | 0.00 | 90.00 | 23.93 | 23.4 | undef. | 90.00 | 359.02 |
| Moon | 6.68 | 655.73 | 1.54C | |||||
| Mars | 25.19 | 317.68 | 52.89 | 24.62 | 25.19 | 317.67 | 52.88 | 350.89 |
| Jupiter | 3.13 | 268.05 | 64.49 | 9.93D | 3.12 | 268.06 | 64.50 | 870.54D |
| Saturn | 26.73 | 40.60 | 83.54 | 10.66D | 26.73 | 40.59 | 83.54 | 810.79D |
| UranusE | 97.77 | (77.43) | (15.10) | (17.24)D | 82.23 | 257.31 | -15.18 | -501.16D |
| Neptune | 28.32 | 299.36 | 43.46 | 16.11D | 28.33 | 299.40 | 42.95 | 536.31D |
| PlutoE | 122.53 | (133.02) | (-9.09) | (153.29) | 60.41 | 312.99 | 6.16 | -56.36 |
| A with respect to the ecliptic of 1850 | ||||||||
| B at 16° latitude; the Sun's rotation varies with latitude | ||||||||
| C with respect to the ecliptic; the Moon's orbit is inclined 5°.16 to the ecliptic | ||||||||
| D from the origin of the radio emissions; the visible clouds generally rotate at different rate | ||||||||
| E NASA's listed tilt is inconsistent with their listed north pole and rotation for these planets; values in (parenthesis) have been reinterpreted to match their listed tilt | ||||||||
Read more about this topic: Axial Tilt
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