双语新闻：最近的研究提供了关于神秘行星的新信息

Eris, a very small planet similar in size to Pluto, has remained a mystery since its discovery in 2005. The American spacy agency, NASA, explored Pluto in 2015 using its spacecraft New Horizons. Eris - about 40 percent farther from the sun - has never been visited.

厄里斯是一颗与冥王星大小相似的小行星，自2005年被发现以来一直是个谜。2015年，美国国家航空航天局(NASA)利用其航天器“新视野号”探索了冥王星。阋神星——距离太阳大约40%——从未被造访过。

But scientists are gaining a fuller understanding of Eris and its differences with Pluto. A recent study provides details about the little planet's structure and composition based on its relationship with its moon Dysnomia.

但科学家们正在对厄里斯及其与冥王星的不同之处有更全面的了解。最近的一项研究根据其与卫星Dysnomia的关系提供了这颗小行星的结构和组成的细节。

Eris, researchers said recently, appears to have a rocky inside under a level of ice. Pluto also has an icy outside with rock below, but has a higher ice content and is thought to have an underground liquid ocean.

研究人员最近表示，厄里斯似乎在冰层下有一块岩石。冥王星也有冰的表面，下面是岩石，但它的冰含量更高，并且被认为有一个地下液态海洋。

"We already knew that Eris is more rock-rich than Pluto, but what we didn't know was whether Eris had separated the rock from the ice," said study lead writer Francis Nimmo of the University of California Santa Cruz. The study appeared in the publication Science Advances.

“我们已经知道厄里斯比冥王星拥有更多的岩石，但我们不知道的是厄里斯是否将岩石从冰中分离出来，”加州大学圣克鲁兹分校的研究报告首席作者弗朗西斯·尼莫说。这项研究发表在《科学进展》杂志上。

Nimmo said Eris got hot enough at some point in history to melt, and all the rock sank to the center.

尼莫说厄里斯在历史上的某个时刻温度足够高，融化了，所有的岩石都下沉到中心。

"The ice is not motionless but is experiencing a slow churning motion, driven by leftover heat from the inside. Most likely there is no liquid ocean inside Eris," Nimmo said.

“冰并不是静止不动的，而是在内部剩余热量的驱动下，经历着缓慢的搅动运动。厄里斯内部很可能没有液态海洋，”尼莫说。

Eris has a diameter of about 2,326 kilometers. Pluto's is a little bigger at about 2,370 km. Both are smaller than the Earth's moon, which has a diameter of 3,475 kilometers. Because of the greater amount of rock, which is denser than ice, Eris has about 25 percent more mass than Pluto.

厄里斯的直径约为2326公里。冥王星的距离要大一些，约为2370公里。这两颗卫星都比直径为3475公里的月球小。因为厄里斯有更多的岩石，密度比冰大，所以厄里斯的质量比冥王星多25%。

"As I like to think of it, take Pluto and add every single asteroid in the asteroid belt, and you get Eris," said study co-writer Mike Brown, one of the three scientists who discovered Eris.

“我喜欢这样想，把冥王星加上小行星带里的每一颗小行星，就得到了厄里斯，”该研究的合著者迈克·布朗说，他是发现厄里斯的三位科学家之一。

Eris orbits at an average of about 68 times further from the sun than Earth. It completes a full turn around the sun in 557 years.

厄里斯的轨道距离太阳的平均距离是地球的68倍。它绕太阳转一圈需要557年。

The moon, Dysnomia, is about 700 kilometers in diameter and made up mostly of ice.

这颗名为Dysnomia的卫星直径约700公里，主要由冰组成。

"Just like the Earth-moon system, tides on Eris slowly push Dysnomia away and slow down the spin of Eris. This process has gone to completion: Eris and Dysnomia always present the same face to the other," Nimmo said.

“就像地月系统一样，厄里斯上的潮汐会慢慢地把Dysnomia推开，减慢厄里斯的旋转速度。这个过程已经完成了:厄里斯和Dysnomia总是以同一张脸面对对方，”Nimmo说。

Pluto has this same system with its moon Charon, while the Earth-moon system differs.

冥王星和它的卫星卡戎有相同的系统，而地月系统不同。

"The moon always presents the same face to the Earth, but the Earth does not return the favor," Nimmo said.

尼莫说:“月亮总是以同样的面孔面对地球，但地球却没有回报。”

Eris and Pluto are located beyond Neptune, the outermost of our solar system's eight bigger planets. The International Astronomical Union, which sets definitions for planetary science, recognizes five very small planets known as dwarf planets - Ceres, Haumea and Makemake, in addition to Eris and Pluto. Eris is the most massive of them.

厄里斯和冥王星位于海王星之外，海王星是太阳系八大行星中最外层的一颗。制定行星科学定义的国际天文学联合会认定，除了阋神星和冥王星外，还有五颗非常小的行星被称为矮行星——谷神星、妊神星和牧神星。厄里斯是其中质量最大的。

The new findings fill in some questions about Eris.

新的发现填补了关于厄里斯的一些问题。

"Each of the largest dwarf planets is unique and we should be cautious about inferring too much from what we know about Pluto," Brown said.

布朗说:“每一颗最大的矮行星都是独一无二的，我们应该谨慎，不要从我们对冥王星的了解中推断太多。”