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Pluto is a cold little world far from us in the outerreaches of our solar system.
But researchers believe Pluto may have been born as a muchwarmer place.
They say it may even have sheltered a subsurface orunderground ocean – one that still exists today.
A report on Pluto appeared earlier this month in thescientific journal Nature Geosciences.
The lead author was Carver Bierson, a planetary scientist atthe University of California Santa Cruz.
In the report, researchers pointed to evidence for a"hot start" situation at Pluto's beginning, some 4.5 billion yearsago.
Their study was based on images of the dwarf planet'ssurface as well as computer models of the subsurface.
"When Pluto was forming, new material would have beencoming in and impacting its surface," Bierson said. "Each impact islike an explosion that would warm the nearby area."
Bierson explained that if Pluto had formed slowly, thesurface would have cooled between each impact and generally stayed very cold.
But if Pluto had formed quickly, the surface may not havehad time to cool down.
"If Pluto formed in less than 30,000 years," hesaid, "the heat from these impacts could have been sufficient to lead toan early ocean."
Pluto may have an icy outer shell hundreds of kilometersthick atop an ocean of water, possibly mixed with salts and ammonia.
A solid rocky core could lie below, Biersonsaid.
The researchers believethat parts of the ocean would gradually freeze over time.
Water expands as itfreezes, and cracks on Pluto's surface may be evidence of this.
At present, Pluto'ssurface temperature is about minus 230 degrees Celsius.
A subsurface oceancould make Pluto a possible, although unlikely, candidate for having livingorganisms.
Bierson said it waspossible that contact between water and the rocky core could have createdcertain chemical ingredients.
"Are those theright ingredients for life?" Bierson asked. "We don't know.
We need to learn moreabout how life forms, or how life could form, to find these answers."
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美 [dwɔːrf]
adj. related to or involving something that is much smallerthan the usual size
I am guilty of being a dwarf. I've been on trial for that myentire life.
我有罪，因为我是个侏儒，我的一生都为此遭受审判[权利的游戏]
美 [ɪnˈɡriːdiənt]
n. a part or piece of something
冥王星是一个栖息在我们的太阳系边缘的寒冷小星球。但研究人员认为，冥王星诞生时可能是一个在温暖得多的地方。他们说，它甚至可能荫蔽了一个至今仍然存在的地下海洋。本月早些时候，科学杂志《自然地球科学》发表了一篇关于冥王星的报告。第一作者是加州大学圣克鲁斯分校的行星科学家卡弗·比森(CarverBierson)。在这份报告中，研究人员指出了大约45亿年前冥王星“热开端”的证据。他们的研究是基于这颗矮行星表面的图像和计算机模拟的地下表面结果。比尔森说:“在冥王星形成的时候，新的物质会进入并撞击它的表面。”“每次撞击就像一次爆炸，会使附近地区升温。”比尔森解释说，如果冥王星是缓慢形成的，那么它的表面在每次撞击间隙都会冷却下来，通常会保持非常冷的状态。但如果冥王星是迅速形成的，表面可能没有时间冷却下来。“如果冥王星在不到3万年的时间内形成，”他说，“这些撞击产生的热量可能足以形成早期的海洋。”冥王星可能有一层几百公里厚的冰壳，覆盖在可能含有盐和氨的海洋之上。比尔森说，地下可能有一个坚硬的岩石内核。研究人员认为，随着时间的推移，部分海洋将逐渐冻结。水结冰时会膨胀，冥王星表面的裂缝可能就是证据。目前，冥王星的表面温度约为零下230摄氏度。地下海洋可能使冥王星成为有生命有机体存在的星球(尽管可能性不大)。Bierson说，水和岩石核之间的接触可能产生了某些化学成分。“它们是有助于生命存活的正确成分吗?”Bierson问道。“尚不可知。我们需要更多地了解生命是如何形成的，或者说如果形成生命，以寻求真正的答案。”
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