The function T(a) = a’ models Kepler's Third Law. The period T (in Earth years) is the time it takes a planet to complete one orbit about the sun as a function of the planet's average distance from the sun, measured in astronomical units (AU). What do you think are some key features of the graph of T(a)? Use a graphing calculator to graph T(a) and examine its features. Then find the time it takes for Neptune, with an average distance from the sun of 30.06 AU, to complete its orbit of the sun