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## Planetocentric Systems

For solar system bodies the IAU differentiates between planetocentric and planetographic body-fixed coordinates : Planetocentric latitude refers to the equatorial plane and the polar axis, planetographic latitude is defined as the angle between equatorial plane and a vector through the point of interest that is normal to the biaxial ellipsoid reference surface of the body. Both latitudes are identical for a spherical body. Planetocentric longitude is measured eastwards (i.e. positive in the sense of rotation) from the prime meridian. Planetographic longitude of the sub-observation point increases with time, i.e. to the west for prograde rotators and to the east for retrograde rotators. All systems defined in the following are planetocentric.

Table 6 gives the orientation of the planetary rotation systems for all major planets at epoch and their change with time. These are defined by the equatorial attitude of the rotation axis and the prime meridian angle . Data are taken from [S. Table 15.7] which is identical to the table given by Davies et al. (1996). The ascending node right ascensions are given by . The respective transformation matrices are

 (37)

where and are defined in eqn.1 and 2.

 Name Sun 286.13 63.87 84.10 +14.1844000 Mercury 281.01 -0.003 61.45 -0.005 329.71 +6.1385025 Venus 272.72 67.15 160.26 -1.4813596 Earth 0.00 -0.641 90.00 -0.557 190.16 +360.9856235 Mars 317.681 -0.108 52.886 -0.061 176.868 +350.8919830 Jupiter III 268.05 -0.009 64.49 +0.003 284.95 +870.5360000 Saturn III 40.58 -0.036 83.54 -0.004 38.90 +810.7939024 Uranus III 257.43 -15.10 203.81 -501.1600928 Neptune 299.36 +0.70 43.46 -0.51 253.18 536.3128492- 0.48 (where N= 359.28 +54.308) Pluto 313.02 9.09 236.77 -56.3623195

Subsections

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Markus Fraenz 2017-03-13