Assume that Mars and Earth are in the same plane and that their orbits around the Sun are circles (Mars is ≈230×10^6km from the Sun and Earth is ≈150×10^6km from the Sun).
a) How long would it take a message sent as radio waves from Earth to reach Mars when Mars is nearest Earth?

b) How long would it take a message sent as radio waves from Earth to reach Mars when Mars is farthest from Earth?