The average distance Earth-Sun is called the astronomical unit (AU). Refer to the table of planetary orbital data.
(a) From the table, compute the ratios (period)^2/a^3 for your 2 favorite planets (any two planets of your choice, other than the Earth).
(b) Explain why these ratios should be close to one. You should proceed as follows:
according to Kepler's third law, T^2Earth/a^3Earth=T^2Planet/a^3Planet, and deduce that this ratio is equal to 1 for the Earth (in appropriate units).