单选题 Edwin Hubble Edwin Hubble changed our ideas about the universe and how it developed. The work of few other scientists changed our understanding of 【51】 suddenly. He made his most important discoveries in the 1920s. Today, other scientists continue the work he began back then. Edwin Powell Hubble was born in 1889 in Marshfield, Missouri. He 【52】 his early years in the state of Kentucky. Then he moved with his family to Chicago, Illinois. He attended the University of Chicago, taking mathematics and astronomy 【53】 his specialty. As a student, Hubble was also a member of the University''s basketball team and an excellent boxer. Several people urged him 【54】 for the world heavy weight boxing championship after college. Instead he decided to continue his 【55】 . In his first observations from Mount Wilson, California, Hubble used a telescope with one-hundred fifty-two and began 【56】 more and more distant objects. His first great discovery was made 【57】 he recognized a Cepheid variable star. Cepheid variable stars are stars whose brightness changes at regular periods. Hubble then began to observe more details about galaxies. He studied their shapes and brightness. By 1925, he had made enough observations to say that the universe is organized into many shapes and sizes. As stars differ from one another, he said, 【58】 galaxies. According to his observations, the galaxies have a center, and arms of matter that seem to the center like a pinwheel. Other are shaped 【59】 baseballs or eggs. A few have no special 【60】 Hubble proposed a system to describe galaxies by their shape. His system is still used today. He also showed that 【61】 are similar in the kinds of bright objects they contain. All galaxies, 【62】 , are related to each other much as members of a family are related to each other. In the late 1920s, Hubble studied the movement of galaxies through space. His investigation led to the most important 【63】 discovery of the 20th century—the expanding universe. Hubbies discovery 【64】 a major change in our ideas of the universe. The universe had not been quiet and unchanging since the beginning of time, as many people had thought. It was expanding. The expanding often is 【65】 the Big Bang.