【科学60秒】冥王星卫星身世之谜_英语听力练习mp3下载-科学-沪江听力酷

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【科学60秒】冥王星卫星身世之谜

听力简介：

Imagine a pinball machine on multi-ball mode—only the balls are the size of planets. The early solar system was such a rough-and-tumble place.

That ____1____ environment produced the occasional literally Earth-shattering collision. The moon, for instance, is believed to have formed from debris ____2____ by a Mars-size object careening into our young planet.

Now, new research indicates that Pluto may have suffered a similar fate. According to planetary scientist Robin Canup, all three of Pluto’s satellites could ____3____ to a single impact.

An impact has long been ____4____ for the birth of Charon, the largest Plutonian moon, but Canup ran impact simulations to show that Nix and Hydra, two much smaller satellites discovered in 2005, may be debris from the same collision. Her study appears in The Astronomical Journal.

A simulated low-speed crash between two____5____ sized planetoids yields a Pluto and a Charon, plus an icy debris disk that could coalesce into a Nix and a Hydra. That means that the small satellites should still be pretty icy—a prediction that may be tested as soon as 2015, when NASA’s New Horizons probe reaches the area. If the probe finds that Nix and Hydra are mostly ice, it'll show Canup’s simulation to be a smashing success.
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