閱讀理解
Do you know how many stars there are in the universe?The answer is MANY! Our sun is one of about 100 billion stars in our galaxy, the Milky Way.But the Milky Way is just one of billions of galaxies that we know about! Some other scientists say there are 2,000,000,000,000,000,000 stars!
The largest star that we know about is called the Pistol Star (手槍星).The Pistol Star is closer to the center of the Milky Way than we are.Because of space dust we can’t see it with the naked eye (肉眼).It’s about 100 times the size of our Sun, and 10,000,000 times as bright as the Sun!
The closest star to the Earth is the Sun! The Sun is about 93 million miles away.We measure bigger distances in space in light years, and one light year is about 6,000,000,000,000 miles.Besides the Sun, Proxima Centauri (半人馬比鄰座星) is the closest star at 4.2 light years away.Some of the brightest stars are more distant-Rigel (參宿七),in the constellation Orion (獵戶星座),is the seventh brightest star in the sky but is 900 light years away.To see the faraway stars, scientists use the Hubble Space Telescope (啥勃空間望遠鏡).Hubble has been stars that are 12 billion light years away!
A star’s color has a lot to do with its temperature.A blue-white star is very dense (密集的) and hot.When a star becomes red, its energy.Has begun to fade (消失).Therefore, a star that is nearing the end of its life is called a red giant (紅巨星).While humans grow smaller in old age, stars grow bigger until they die.In the far future, maybe our sun will become a red giant and destroy the Earth! Luckily, it’ll be a long time before we have to think about that problem.
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