VOA慢速英语2020 冥王星形成初期温度非常高（在线收听）

Pluto is a cold little world far from us in the outer reaches of our solar system.But researchers believe Pluto may have been born as a much warmer place.They say it may even have sheltered a subsurface or underground ocean– one that still exists today.

冥王星是一个寒冷的小星球，距离我们很远，位于太阳系的边缘。但研究人员认为，冥王星诞生时可能是一个温暖得多的地方。他们表示，冥王星那时甚至可能藏有一个地下海洋，且至今仍然存在。

A report on Pluto appeared earlier this month in the scientific journal Nature Geosciences.The lead author was Carver Bierson, a planetary scientist at the University of California Santa Cruz.

本月早些时候，一篇有关冥王星的报告发表在科学期刊《自然·地球科学》上。其主要作者卡佛·比尔森是加州大学圣克鲁兹分校的行星科学家。

In the report, researchers pointed to evidence for a "hot start" situation at Plutos beginning, some 4.5 billion years ago.Their study was based on images of the dwarf planets surface as well as computer models of the subsurface.

在报告中，研究人员指出有证据支持，在大约45亿年前，冥王星形成初期处于一种“热启动”的情况。他们的研究基于这颗矮行星表面的图像及其内部结构的计算机模型。

"When Pluto was forming, new material would have been coming in and impacting its surface," Bierson said."Each impact is like an explosion that would warm the nearby area."

比尔森说：“冥王星形成时，新的物质会进入并冲击其表面。每次撞击都像爆炸一样，使得周边温度升高。”

Bierson explained that if Pluto had formed slowly, the surface would have cooled between each impact and generally stayed very cold.But if Pluto had formed quickly, the surface may not have had time to cool down.

比尔森解释称，如果冥王星形成的速度缓慢，其表面则会在每次撞击的间隙冷却下来，且通常会保持非常冷的状态。但如果冥王星形成速度很快，那么其表面可能就来不及冷却。

"If Pluto formed in less than 30,000 years," he said,"the heat from these impacts could have been sufficient to lead to an early ocean."

他说：“如果冥王星是在不到3万年的时间内形成的，那么这些撞击产生的热量可能足以形成早期的海洋。”

Pluto may have an icy outer shell hundreds of kilometers thick atop an ocean of water, possibly mixed with salts and ammonia.A solid rocky core could lie below, Bierson said.

冥王星可能有一层厚达数百公里的冰壳，下面是一片由水构成的海洋，里面很可能混杂着盐和氨。海洋下面可能是坚硬的岩核，比尔森对此说道。

The researchers believe that parts of the ocean would gradually freeze over time.Water expands as it freezes, and cracks on Plutos surface may be evidence of this.At present, Plutos surface temperature is about minus 230 degrees Celsius.

研究人员认为，随着时间推移，部分海洋会逐渐结冰。水结冰后会膨胀，而冥王星表面的裂缝可能就是这方面的证据。目前，冥王星的表面温度约为零下230摄氏度。

A subsurface ocean could make Pluto a possible, although unlikely, candidate for having living organisms.

地下海洋或使冥王星成为可以生存有生命有机体的候选星球，虽然这种可能性不大。 

Bierson said it was possible that contact between water and the rocky core could have created certain chemical ingredients.

比尔森称，水与岩核之间的接触可能产生了某些化学成分。 

"Are those the right ingredients for life?" Bierson asked."We dont know. We need to learn more about how life forms, or how life could form, to find these answers."

比尔森问道：“那些化学成分利于生命存活吗？”“我们不知道。为了找到这些答案，我们需要更多地了解生命是如何形成的，或者说怎样才能形成生命。”

Im John Russell.

约翰·拉塞尔报道。