Pluto May Have Started Out Very Hot
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.
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.
In the report, researchers pointed to evidence for a "hot start" situation at Pluto's beginning, some 4.5 billion years ago. Their study was based on images of the dwarf planet's surface as well as computer models of the subsurface.
"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."
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.
"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."
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.
The researchers believe that parts of the ocean would gradually freeze over time. Water expands as it freezes, and cracks on Pluto's surface may be evidence of this. At present, Pluto's surface temperature is about minus 230 degrees Celsius.
A subsurface ocean could make Pluto a possible, although unlikely, candidate for having living organisms.
Bierson said it was possible that contact between water and the rocky core could have created certain chemical ingredients.
"Are those the right ingredients for life?" Bierson asked. "We don't know. We need to learn more about how life forms, or how life could form, to find these answers."
I'm John Russell.
The evidence against him was purely circumstantial.
I'd already measured out the ingredients
The state allotted them large quantities of chemical fertilizer.
The air is thick with acrid smoke from the fires.
5.Their study was based on images of the dwarf planet's surface as well as computer models of the subsurface.
as well as 而且
They visited some factories, hospitals as well as the school.
Whoever did him in removed a man who was brave as well as ruthless.
6.Their study was based on images of the dwarf planet's surface as well as computer models of the subsurface.
be based on 以...为基础
We find her evidence to be based on a degree of oversensitivity.
Both countries agreed that normal relations would be based on non-interference in each other's internal affairs.
冥王星是一个栖息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温暖的地方 。他们指出，它甚至可能荫蔽了一个至今仍然存在的地下海洋 。
本月初，《自然·地球科学》月刊发表了一项研究冥王星的报告 。首席作者卡佛·比尔森是来自加州大学圣克鲁斯分校的行星科学家 。
在这项报告里，研究人员指出了大约45亿年前冥王星初期时可能存在“炎热开端”的证据 。他们的研究是基于这颗矮行星表面图像以及内部结构的计算机内部结果 。
比尔森表示：“冥王星形成时，新的物质会抵达这里并撞击它的表面 。”“每次撞击就像一次爆炸，导致周边的区域升温 。”
比尔森还解释称，如果冥王星是缓慢形成的，那么它的表面会在每次撞击的间隙冷却下来，通常会保持非常寒冷的状态 。但如果冥王星形成的速度很快，表面可能没有机会冷却下来 。
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表面 。比尔森指出，地下可能是坚硬的岩核 。
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 。
“它们是有助于生命存活的正确成分吗？尚不可知 。为了找寻真香，我们需要更多地去了解生命是如何形成的，或者说怎样才能形成生命 。”