## Calculate the average distance of Mercury, Venus and Earth to Mars. Which one of these planets is the closest to Mars on average?

The table below lists the average distance R to the Sun and orbital period T of the first planets: Distance Orbital Period
Mercury 0.39 AU 88 days
Venus 0.72 AU 225 days
Earth 1.00 AU 365 days
Mars 1.52 AU 687 days
(a) Calculate the average distance of Mercury, Venus and Mars to the Earth.
Which one of these planets is the closest to Earth on average?
(b) Calculate the average distance of Mercury, Venus and Earth to Mars.
Which one of these planets is the closest to Mars on average?
(c) What do you expect for the other planets?
Hint: Assume circular orbits and use symmetries to make the distance calculation easier. You can
approximate the average distance by using four well-chosen points on the planet’s orbit.

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