!MERCURY Mercury is the first planet of the Solar system whose orbit is nearest the sun. It is closest to the Sun and has a diameter of 4,849 kms (3,031 miles). It has no satellites or moons. The average distance of Mercury to the Sun is 57.6 million kms (36 million miles). It orbits the Sun in 88 days. Its speed along its eliptical orbit is 176,000 kms (110,000 miles) per hour. It has no atmosphere. Its surface is cratered. It is one-seventeenth the size of the earth, but is of greater density. It is visible just before the sun rises and after it sets, but that very seldom owing to the sun's neighbourhood.