Flights to Mercury. Because of Mercury's size and nearness to the brightly shining sun, the planet is often hard to see from the earth without a telescope. At certain times of the year, Mercury can be seen low in the western sky just after sunset. At other times, it can be seen low in the eastern sky just before sunrise. View Table Mercury at a glance Orbit.
Mercury moves around the sun faster than any other planet.
The ancient Romans named it Mercury in honor of the swift messenger of their gods. The earth goes around the sun once every 365 days, or one year. As Mercury moves around the sun, it rotates on its axis, an imaginary line that runs through its center. Until 1965, astronomers believed that Mercury rotated once every 88 earth-days, the same time the planet takes to go around the sun. If Mercury did this, the sun would seem to stand still in Mercury's sky.