题型:阅读理解 题类:常考题 难易度:普通
新人教版2020-2021学年高中英语必修第三册Unit 4 Section A同步习题
The ringed planet Saturn has 53 known moons. And another one may be on the way. NASA's Cassini-Huyens space probe has spotted(发现)a small shape in Saturn's outermost ring. It suggests the existence of a new moon. The moon has not been directly spotted yet, but scientists have already given it a nickname—Peggy.
The probe's findings were published in the journal Icarus. Casssini has been observing the ringed planet and its surroundings since 2004. Saturn is a big and powerful world. With a diameter of 74, 732 miles, it is 9. 5 times the size of Earth. It spins very quickly, and takes only 11 hours to spin fully on its axis(轴). The planet is located about 885. 9 million miles from the sun and has an average temperature of-285 degrees Fahrenheit.
Peggy will be joining a large community. Saturn has thousands of rings. The outermost ring, called the A Ring, is the largest and brightest. It measures 750 miles long and 6 miles wide. Saturn's rings are made up of rock, dust and ice, and are constantly gathering space matter. As this material gathers and clumps together, moons are born.
If Peggy is a new moon, it is also a tiny one, measuring only 0. 5 miles in diameter. But there is no telling how big this baby will grow over time." We've never seen anything like this before," said astronomer Carl Murray in a statement. He is the lead author of the Icarus report." We may be looking at an act of birth, where this object is leaving the rings and heading off to be a moon in its own right." Once that happens, it will be given a formal name.
However, this mini moon may be one of Saturn's last moons. The formation of all its moons, new and old, big and small, has used up much of the rings' raw material. After 4. 5 billion years, Saturn may have finally revealed all its babies.
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