Once classified as a true planet, icy Pluto is now considered one of the more than 40 dwarf planets in our solar system.

它曾一度被划归为行星，冰冷的冥王星目前被认为是我们太阳系的40多个矮行星之一。

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Pluto was demoted to a newly created category, "dwarf planet," in 2006, partly because of the discovery a year earlier of Eris, another icy body from Pluto's neighborhood.

冥王星在2006年被降格至一个新创造的类别，“矮行星”，部分原因是在那之前一年，在冥王星的轨道附近，一颗名叫厄里斯的冰态天体被发现。

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Hubble recently showed a fourth moon orbiting Pluto. Astronomers temporarily named it P4. The moon is the smallest to be discovered around the icy dwarf planet.

哈勃太空望远镜最近发现了第四颗绕行冥王星的卫星。天文学家们暂时把它命名为P4。该是迄今为止发现的围绕这颗冰雪覆盖的矮行星的最小的卫星。

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