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B. 1.3 billions of
C. 1.3 billion
D. 1.3 billion of
There are near people in China.
A. 1.3 billion B. billions of 1.3
C. 1.3 billions D. billion of 1.3
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B. billion of
C. 13 billions
D. 1.3 billion
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 (手枪星). The PistolStar is closer to the center
of the Milky- May 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, and10,000,000 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 about6,000,000,000,000 miles. Besides the Sun, Proxima
Centauri (半人马比邻座星) isthe closest star at 4.2 light years away: Some of the brightest stars are more
distant Rigel (参宿七), in the constellation Orion (猎户星座), is the seventh brightest star inthe sky but is 900
light years away. To see the faraway stars, scientists use the Hubble Space Telescope (哈勃空间望远镜).
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-wbite 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(红巨星). Whilehumans grow smaller in old age, stars grow bigger until they die. In thefar
future, maybe our sun will become a red giant and destroy the Earth! Luckily, it'll be a longtime before we have
to think about that problem.
A. the sun
B. the moon
C. the Pistol Star
D. Rigel
B. kilometers
C. miles
D. light years
B. Rigel.
C. Proxima Centauri.
D. The Pistol Star
B. red
C. yellow
D. red and blue
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