Brainlies ! 1. a student made the following observations about astronomical bodies. observation 1: mars reverses its direction of motion in the night's sky. observation 2: the stars move across the sky. which observation(s) can be explained using the heliocentric model but not the geocentric model? only observation 1 only observation 2 both observation 1 and observation 2 neither observation 1 nor observation 2 2. the following table shows the duration of a year on some unknown planets of equal mass. duration of year planet duration of year y 224 days z 320 days which of the following best explains which planet is closer to the sun? planet y, because gravity is directly proportional to square of distance planet z, because gravity is directly proportional to the square of distance planet z, because the sun exerts a greater gravitational force on it than on planet y planet y, because the sun exerts a greater gravitational force on it than on planet z