【科学60秒】土星环——卫星的残迹_英语听力练习mp3下载-科学-沪江听力酷

后台管理反馈贡献

【科学60秒】土星环——卫星的残迹

听力简介：

Galileo first ______1_____ Saturn’s rings 400 years ago. But since then, scientists have ______2_____ how they got there. Because the rings are almost pure water ice—and material in the outer solar system is generally an ice-rock mix. But a new analysis in the journal Nature may have solved the mystery.
Today, Saturn's only massive moon is Titan. But Saturn’s fellow gas giant planet Jupiter has four big moons. So Saturn might once have had more—one of which could have had a rocky core surrounded by a shell of water ice. That moon would have interacted with a disk of gas surrounding Saturn at the time, dragging its orbit closer and closer.
As the moon ______3_____, tidal forces would have flexed its icy shell, stripping off chunks to build rings a thousand times more massive than Saturn has today. Eventually, ice boulders in the rings would have ______4____ each other, spreading out the rings, and causing the outer edge to spawn icy moons—the small ones we find orbiting Saturn today.
As for that ancient moon’s rocky core? Saturn probably _____5_____. Leaving Titan unique. And leaving scientists with a puzzle they finally may have solved.
【视听版科学小组荣誉出品】