World Country Geography Essentials

Author: Ren Yibin
Publisher:
Publish Date: 2005-01-01
Features: For thousands of years, humans have been exploring the mysteries of the universe: the light and heat of the sun, the alternation of day and night, the phases of the moon, the rotation and cycles of the stars in the sky, the recurring changes of seasons, the appearance and disappearance of meteors, the visitation of comets, the wonders of solar and lunar eclipses, and the life in outer space. Five hundred years ago, Copernicus proposed that the Earth was not at the center of the universe, nor did the sun revolve around the Earth, but rather the Earth revolved around the sun. His views were no less than a bombshell exploding overhead at the time. But soon, people not only knew that the Earth was not at the center of the universe but also learned that the sun was just an ordinary star in the Milky Way. What is even more astonishing is that subsequent scientific research has found that the universe contains about 100 billion galaxies similar to the Milky Way; now, the farthest known galaxy is 13.7 billion light-years away from Earth! A galaxy refers to a large unit composed of many stars. Some are irregular and indistinguishable in shape, while many spiral galaxies resemble windmills, and our Milky Way is a spiral-type star system. Galaxies are the "islands" of vast stars in the universe and are also one of the largest and most beautiful celestial systems in the universe. Stars are like brilliant gems embedded in the night sky, each one performing a diverse and colorful life, either tragic or peaceful. Our universe is so magnificent and diverse, and people can't help but ask: How was it formed? How did it gradually evolve into the form we see today? When physicist Albert Einstein established the great theory of general relativity in 1915, he already recognized that his theory would confirm a breathtaking prophecy: the universe is expanding. However, at that time, most astronomers believed that the universe had always been the same since ancient times and would not change over time. P16