In Roman mythology Mercury is messenger of the gods, and son of the god Jupiter. Mercury is the planet closest to the sun. Its distance from the sun is approximately 58 million km (about 36 million miles); its diameter is 4875 km (3030 miles); its volume and mass are about : that of the earth; and its density is approximately equal to that of the earth. Mercury revolves about the sun in a period of 88 days. Radar observations of the planet show that its period of rotation is 58.7 days, or two-thirds of its period of revolution. The planet, therefore, rotates one and a half times during each revolution. …
