Answer: i hope this helps :)
-- 687 days
-- After years of analysis, Kepler discovered that Mars's orbit was likely to be an ellipse, with the Sun at one of the ellipse's focal points. This, in turn, led to Kepler's discovery that all planets orbit the Sun in elliptical orbits, with the Sun at one of the two focal points.
-- From our point of view as we race around the Sun, Mars is falling behind; consequently, we see Mars moving in a retrograde direction from night to night across the sky. Since the Earth always moves around the Sun faster than Mars, you might imagine that Mars's motion will always be retrograde.
-- Basically, that planets do not move with constant speed along their orbits. Rather, their speed varies so that the line joining the centers of the Sun and the planet sweeps out equal parts of an area in equal times. The point of nearest approach of the planet to the Sun is termed perihelion