天文学家发现第四颗冥王星卫星
文章来源:未知 文章作者:enread 发布时间:2011-07-21 02:32 字体: [ ]  进入论坛
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Astronomers1 using the Hubble Space Telescope discovered a fourth moon orbiting the icy dwarf2 planet Pluto3(冥王星) . The tiny, new satellite – temporarily designated P4 -- was uncovered in a Hubble survey searching for rings around the dwarf planet. The new moon is the smallest discovered around Pluto. It has an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Charon, Pluto's largest moon, is 648 miles (1,043 km) across, and the other moons, Nix and Hydra4, are in the range of 20 to 70 miles in diameter (32 to 113 km).

"I find it remarkable5 that Hubble's cameras enabled us to see such a tiny object so clearly from a distance of more than 3 billion miles (5 billion km)," said Mark Showalter of the SETI Institute in Mountain View, Calif., who led this observing program with Hubble.

The finding is a result of ongoing6 work to support NASA's New Horizons mission, scheduled to fly through the Pluto system in 2015. The mission is designed to provide new insights about worlds at the edge of our solar system. Hubble's mapping of Pluto's surface and discovery of its satellites have been invaluable7 to planning for New Horizons' close encounter.

"This is a fantastic discovery," said New Horizons' principal investigator8 Alan Stern of the Southwest Research Institute in Boulder9, Colo. "Now that we know there's another moon in the Pluto system, we can plan close-up observations of it during our flyby."

The new moon is located between the orbits of Nix and Hydra, which Hubble discovered in 2005. Charon was discovered in 1978 at the U.S. Naval10 Observatory11 and first resolved using Hubble in 1990 as a separate body from Pluto.

The dwarf planet's entire moon system is believed to have formed by a collision between Pluto and another planet-sized body early in the history of the solar system. The smashup(猛撞,惨败) flung material that coalesced12(合并,结合) into the family of satellites observed around Pluto.

Lunar rocks returned to Earth from the Apollo missions led to the theory that our moon was the result of a similar collision between Earth and a Mars-sized body 4.4 billion years ago. Scientists believe material blasted off Pluto's moons by micrometeoroid(微流星体) impacts may form rings around the dwarf planet, but the Hubble photographs have not detected any so far.

"This surprising observation is a powerful reminder13 of Hubble's ability as a general purpose astronomical14 observatory to make astounding15, unintended discoveries," said Jon Morse, astrophysics(天体物理学) division director at NASA Headquarters in Washington.

P4 was first seen in a photo taken with Hubble's Wide Field Camera 3 on June 28. It was confirmed in subsequent Hubble pictures taken on July 3 and July 18. The moon was not seen in earlier Hubble images because the exposure times were shorter. There is a chance it appeared as a very faint smudge in 2006 images, but was overlooked because it was obscured.



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1 astronomers 569155f16962e086bd7de77deceefcbd     
n.天文学者,天文学家( astronomer的名词复数 )
参考例句:
  • Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
  • Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪,为什么只有土星有光环。 来自《简明英汉词典》
2 dwarf EkjzH     
n.矮子,侏儒,矮小的动植物;vt.使…矮小
参考例句:
  • The dwarf's long arms were not proportional to his height.那侏儒的长臂与他的身高不成比例。
  • The dwarf shrugged his shoulders and shook his head. 矮子耸耸肩膀,摇摇头。
3 Pluto wu0yF     
n.冥王星
参考例句:
  • Pluto is the furthest planet from the sun.冥王星是离太阳最远的行星。
  • Pluto has an elliptic orbit.冥王星的轨道是椭圆形的。
4 hydra Fcvzu     
n.水螅;难于根除的祸患
参考例句:
  • Let's knock down those hydras and drive them to the sea!让我们铲除祸根,把他们赶到大海去!
  • We may be facing a hydra that defies any easy solution.我们也许正面临一个无法轻易解决的难题。
5 remarkable 8Vbx6     
adj.显著的,异常的,非凡的,值得注意的
参考例句:
  • She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
  • These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。
6 ongoing 6RvzT     
adj.进行中的,前进的
参考例句:
  • The problem is ongoing.这个问题尚未解决。
  • The issues raised in the report relate directly to Age Concern's ongoing work in this area.报告中提出的问题与“关心老人”组织在这方面正在做的工作有直接的关系。
7 invaluable s4qxe     
adj.无价的,非常宝贵的,极为贵重的
参考例句:
  • A computer would have been invaluable for this job.一台计算机对这个工作的作用会是无法估计的。
  • This information was invaluable to him.这个消息对他来说是非常宝贵的。
8 investigator zRQzo     
n.研究者,调查者,审查者
参考例句:
  • He was a special investigator for the FBI.他是联邦调查局的特别调查员。
  • The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。
9 boulder BNbzS     
n.巨砾;卵石,圆石
参考例句:
  • We all heaved together and removed the boulder.大家一齐用劲,把大石头搬开了。
  • He stepped clear of the boulder.他从大石头后面走了出来。
10 naval h1lyU     
adj.海军的,军舰的,船的
参考例句:
  • He took part in a great naval battle.他参加了一次大海战。
  • The harbour is an important naval base.该港是一个重要的海军基地。
11 observatory hRgzP     
n.天文台,气象台,瞭望台,观测台
参考例句:
  • Guy's house was close to the observatory.盖伊的房子离天文台很近。
  • Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。
12 coalesced f8059c4b4d1477d57bcd822ab233e0c1     
v.联合,合并( coalesce的过去式和过去分词 )
参考例句:
  • The puddles had coalesced into a small stream. 地面上水洼子里的水汇流成了一条小溪。
  • The views of party leaders coalesced to form a coherent policy. 党的领导人的各种观点已统一为一致的政策。 来自辞典例句
13 reminder WkzzTb     
n.提醒物,纪念品;暗示,提示
参考例句:
  • I have had another reminder from the library.我又收到图书馆的催还单。
  • It always took a final reminder to get her to pay her share of the rent.总是得发给她一份最后催缴通知,她才付应该交的房租。
14 astronomical keTyO     
adj.天文学的,(数字)极大的
参考例句:
  • He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
  • Houses in the village are selling for astronomical prices.乡村的房价正在飙升。
15 astounding QyKzns     
adj.使人震惊的vt.使震惊,使大吃一惊astound的现在分词)
参考例句:
  • There was an astounding 20% increase in sales. 销售量惊人地增加了20%。
  • The Chairman's remarks were so astounding that the audience listened to him with bated breath. 主席说的话令人吃惊,所以听众都屏息听他说。 来自《简明英汉词典》
TAG标签: moon Hubble Pluto
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