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.
【视听版科学小组荣誉出品】
chaotic stirred up trace back suspected comparably
想象一下一个多球模式的弹球机——不过球的大小和行星差不多。早期的太阳系就是这么个混乱的地方。 在混乱的环境会不时发生惊天动地的碰撞（双关了，不明白的同学可以去讨论帖^-^）。举个例子，人们相信某颗火星大小的行星和一颗年轻行星碰撞后，产生的碎屑形成了月球。 现在一项新研究表示，冥王星的命运何能如出一辙。行星科学家罗宾•克纳普表示，冥王星的三颗卫星都是由某次冲撞产生的。 长期以来，人们都在推测卡戎——最大的冥王星卫星——产生于某次冲撞，但克纳普用模拟冲撞证明尼克斯和许德拉——两颗在2005年发现的小一号卫星——可能也是由同一次冲撞产生的。她的研究刊登在《天文期刊》上。 两颗相似大小的行星在模拟低速碰撞中产生了冥王星和卡戎，还有可以形成尼克斯和许德拉的并碎屑。这意味着两颗小卫星现在应该还是冰天雪地的，而2015年久可以检验这个预言的真假了，到时美国宇航局新视野号探测器就可以到达那个领域。如果探测器发现尼克斯和许德拉上多数都是冰，那么克纳普的模拟实验真是个巨大的成功了。