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Orbital Data for the Planets & Dwarf Planets

Planet Semimajor
of Orbit
to Ecliptic
of Equator
to Orbit
Mercury 0.3871 0.2408 47.9 0.206 7.00 58.65 0
Venus 0.7233 0.6152 35.0 0.007 3.39 -243* 177.3
Earth 1.000 1 29.8 0.017 0.00 0.997 23.4
Mars 1.5273 1.8809 24.1 0.093 1.85 1.026 25.2
Jupiter 5.2028 11.862 13.1 0.048 1.31 0.410 3.1
Saturn 9.5388 29.458 9.6 0.056 2.49 0.426 26.7
Uranus 19.1914 84.01 6.8 0.046 0.77 -0.75* 97.9
Neptune 30.0611 164.79 5.4 0.010 1.77 0.718 29.6

Dwarf Planets

Ceres 2.76596 4.599 17.882 0.07976 10.587 0.378 ~3
Pluto 39.5294 248.54 4.7 0.248 17.15 -6.4* 122.5
Haumea 43.335 285.4 4.484 0.18874 28.19 0.163 ?
Makemake 45.791 309.88 4.419 0.159 28.96 ? ?
Eris 67.6681 557 3.436 0.44177 44.187 > 8 hrs ? ?

* Negative values of rotation period indicate that the planet rotates in the direction opposite to that in which it orbits the Sun. This is called retrograde rotation.

The semimajor axis (the average distance to the Sun) is given in units of the Earth's average distance to the Sun, which is called an AU. For example, Neptune is 30 times more distant from the Sun than the Earth, on average. Orbital periods are also given in units of the Earth's orbital period, which is a year.

The eccentricity (e) is a number which measures how elliptical orbits are. If e = 0, the orbit is a circle. Most of the planets have eccentricities close to 0, so they must have orbits which are nearly circular.

Last modified October 9, 2008 by Randy Russell.

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