Planets



The period of rotation T of a planet is given by:
T2 = (4π2 / GM) r3

where G = universal gravitational constant = 6.67 x 10-11 N m2 kg-2
M = mass of the Sun
r = radius of the orbit of the planet

This is Kepler's 3rd Law of Planetary Motion:

T2 is proportional to r3

PlanetDistance from Sun r (km)Period of Revolution T (years)
Mercury57 900 00086 days
Venus108 200 000225 days
Earth149 600 0001
Mars227 392 0001.88
Jupiter778 300 00011.9
Saturn1 427 000 00029.5
Uranus2 870 000 00084.0
Neptune4 497 000 000164
Pluto5 894 000 000247

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