A)some comets are in highly elongated orbits that come very close to the sun at perihelion. the distance from one such comet to the center of the sun is 6.00×10^9m at perihelion and 3.00×10^12m at aphelion. for this comet's orbit, find the semi-major axis. b)in 2017 astronomers discovered a planet orbiting the star hats-43. the orbit of the planet around hats-43 has semi-major axis 7.41×109m, eccentricity 0.173, and period 4.39 days. find the distance between hats-43 and the planet at its closest approach. express your answer with the appropriate units