If a planet has a semimajor axis of 2 AU (astronomical units)
a) what would the semimajor axis of a superior planet be if the angle of greatest elongation for the inferior planet is 20 degrees as viewed from the superior planet?
b) assuming a day on the superior planet is 30 hours, how long would the inferior planet be visible in the sky after sunset if it is at greatest elongation (answer must be in HR MIN SEC)