Mercury is the planet nearest the sun. It has a diameter of 3,031 miles (4,878 kilometers), about two-fifths the earth's diameter. Mercury's mean distance from the sun is about 36 million miles (57.9 million kilometers), compared to 67,250,000 miles (108,230,000 kilometers) for Venus, the second closest planet.
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.
Orbit. Mercury travels around the sun in an elliptical (oval-shaped) orbit. The planet is about 28,600,000 miles (46 million kilometers) from the sun at its closest point, and about 43.4 million miles (69.8 million kilometers) from the sun at its farthest point. Mercury is about 57 million miles (91.7 million kilometers) from the earth at its closest approach.
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. Mercury travels about 30 miles (48 kilometers) per second, and goes around the sun once every 88 earth-days. The earth goes around the sun once every 365 days, or one year. |
