Mercury is the planet nearest to the sun and the smallest planet in the solar system. It is difficult to see from the earth without a telescope. At certain items 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. Mercury orbits around the sun in an elliptical line, faster than any other planet. It travels about 30 miles per second, and goes around the sun once every 88 eath-days. It is about 29 million miles from the sun at its closest point, and more than 43 million miles from the sun at its farthest point. Mercury's surface appears to be much like that of the moon. It reflects about 6 per cent of the sunlight it receives, about the same as the moon's surface reflects. The planet is dry, extremely hot, and almost airless. The sun's rays are about seven times as strong on Mercury as they are on the earth. Since it does not have enough gases in its atmosphere to reduce the amount of heat and light it receives from the sun, the temperature on the planet is about 625 degrees F. during the day, and lower than 80 degrees F. at night. The plant and animal life of the earth could not live on Mercury, because of the lack of oxygen and the intense heat. Astronomers do not know whether the planet has any form of life. The Romans named it Mercury in honor of the swift messenger of their gods.