The moon is the earth’s only natural satellite. It has been the subject of study by people all over the world for thousands of years. Seen through a telescope, the moon presents a varied landscape to astronomers. From observations using powerful telescopes, analysis of photographs taken by artificial satellites, and information gathered by astronauts who have actually walked on the moon, we know that the surface of the
moon consists of rock and dust. Rock samples brought back by U.S. astronauts can be seen at the National
(A)ir and Space Museum in Washington, D.C.
Many of the moon’s surface features are areas which were thought to be water by early astronomers. We know now, however, that the “seas” on the moon are not bodies of water, but craters formed when the moon was hit by meteors.
There is no atmosphere or water on the moon. No life forms have been found on the moon, either. Astronauts must wear pressurized space suits while on the moon since there is no atmosphere with oxygen. The pulling force of the moon’s gravity is only one-sixth that of earth’s, so a person weighs six times less on the moon than on earth.
Like the earth, the moon depends on the sun for its heat and light. Due to the lack of atmosphere, temperatures on the moon vary widely, from 214 °F on the side facing the sun to about −250 °F on the side facing away from the sun. The moon “shines” because sunlight which strikes the moon is reflected.
【題組】29. _______ are people who study the moon, stars, and other planets through telescopes and by analyzing photographs.