哈特利2彗星处于活跃状态-凯发k8官网

哈特利2彗星处于活跃状态
文章来源:未知 文章作者:enread 发布时间:2011-06-17 02:46 字体: [ ] 
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hartley 2's hyperactive(极度活跃的) state, as studied by nasa's epoxi mission, is 1 in a new paper published in this week's issue of the journal science by an international team of scientists that includes lucy mcfadden of nasa's goddard space flight center in greenbelt, md. after visiting a comet and imaging distant stars for hints of extrasolar(太阳系以外的) planets, you could say the spacecraft used for epoxi had seen its fair share of 2 wonders. but after about 3.2 billion miles (5.1 billion kilometers) of deep space travel, one final wonder awaited the mission's project and science teams. on nov. 4, 2010, the epoxi mission spacecraft flew past a 3 little comet called hartley 2.

"from all the imaging we took during approach, we knew the comet was a little 4 even before flyby," said epoxi project manager tim larson of nasa's jet propulsion laboratory in pasadena, calif. "it was moving around the sky like a knuckleball(不旋转球) and gave my navigators fits, and these new results show this little comet is downright(明白的,直率的) hyperactive."

the epoxi mission found that the strong activity in water release and carbon dioxide-powered jets did not occur equally in the different regions of the comet. during the spacecraft's flyby of the comet -- with closest approach of 431 miles (694 kilometers) -- carbon dioxide-driven jets were seen at the ends of the comet, with most occurring at the small end. in the middle region or waist of the comet, water was released as 5(蒸汽,烟雾) with very little carbon dioxide or ice. the latter findings indicate that material in the waist is likely material that came off the ends of the comet and was redeposited.

"hartley 2 is a hyperactive little comet, spewing out more water than most other comets its size," said mike a'hearn, principal 6 of epoxi from the university of maryland, college park. "when warmed by the sun, dry ice -- frozen carbon dioxide -- deep in the comet's body turns to gas jetting off the comet and dragging water ice with it."

although hartley 2 is the only such hyperactive comet visited by a spacecraft, scientists know of at least a dozen other comets that also are 7 high in activity for their size and which are probably driven by carbon dioxide or carbon monoxide(一氧化物) .

"these could represent a separate class of hyperactive comets," said a'hearn. "or they could be a continuum in comet activity extending from hartley 2-like comets all the way to the much less active, "normal" comets that we are more used to seeing."



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1 xunzms     
adj.详细的,详尽的,极注意细节的,完全的
参考例句:
  • he had made a detailed study of the terrain.他对地形作了缜密的研究。
  • a detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。
2 4ruz8     
adj.天体的;天上的
参考例句:
  • the rosy light yet beamed like a celestial dawn.玫瑰色的红光依然象天上的朝霞一样绚丽。
  • gravity governs the motions of celestial bodies.万有引力控制着天体的运动。
3 bghw8     
adj.古怪的,离奇的;怪诞的,神秘而可怕的
参考例句:
  • from his weird behaviour,he seems a bit of an oddity.从他不寻常的行为看来,他好像有点怪。
  • his weird clothes really gas me.他的怪衣裳简直笑死人。
4 5hay2     
adj.易激动的,轻佻的
参考例句:
  • she gets very skittish when her boy-friend is around.她男朋友在场时,她就显得格外轻佻。
  • i won't have my son associating with skittish girls.我不准我的儿子与轻佻的女孩交往。
5 dhjy2     
n.蒸汽,雾气
参考例句:
  • the cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
  • this new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。
6 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。
7 bkqzs3     
adv.比较...地,相对地
参考例句:
  • the rabbit is a relatively recent introduction in australia.兔子是相对较新引入澳大利亚的物种。
  • the operation was relatively painless.手术相对来说不痛。
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