Exactly one year! A year is the length of time it takes the planet to revolve once around the Sun. Mars takes about 687 Earth-days, or 668.6 Martian-days, to make one complete orbit around the Sun. This is because a Martian day is 39.5 minutes longer than an Earth day.
Mount Everest, at 8,850 metres tall, is often called the highest mountain. But Mauna Kea on the island of Hawaii, is actually taller. The inactive volcano stands 4,245 metres above sea level; and measured from its base, it is 10,203 metres. It should be also noted that Mount Lamlam in Guam, a submerged mountain, stands only 406 meters above sea level, but is 11,330 metres above the floor from the Marianas Trench which lies 400 km to the southwest. Another way to determine the world's highest mountain is to measure the distance from the center of the earth to the peak. Chimborazo volcano in the Andes of Ecuador stands 6,267 metres above sea level, however, its peak is the farthest from the earth's center. This is due to the equatorial bulge caused by the earth's spin. Chimborazo is 6,384,404 metres from the center of the Earth, while Mt. Everest is measured at 6,381,670 metres.