文章来源:未知 文章作者:enread 发布时间:2011-08-18 03:00 字体: [ ]  进入论坛

Earth's Moon could be younger than previously1 thought, according to new research from a team that includes Carnegie's Richard Carlson and former-Carnegie fellow Maud Boyet. Their work will be published online in Nature on August 17. The prevailing2(流行的,一般的) theory of our Moon's origin is that it was created by a giant impact between a large planet-like object and the proto-Earth. The energy of this impact was sufficiently3 high that the Moon formed from melted material that was ejected into space. As the Moon cooled, this magma(岩浆) solidified4 into different mineral components5.

Analysis of lunar rock samples thought to have been derived6 from the original magma has given scientists a new estimate of the Moon's age.

According to this theory for lunar formation, a rock type called ferroan anorthosite, or FAN, is the oldest of the Moon's crustal rocks, but scientists have had difficulty dating FAN samples. The research team, led by Lars E. Borg of the Lawrence Livermore National Laboratory, included Carlson of Carnegie's Department of Terrestrial Magnetism7, Boyet-- now at Université Blaise Pascal--and James N. Connelly of the University of Copenhagen. They used newly refined techniques to determine the age of a sample of FAN from the lunar rock collection at the NASA Johnson Space Center.

The team analyzed8 the isotopes10 of the elements lead and neodymium to place the FAN sample's age at 4.36 billion years. This figure is significantly younger than earlier estimates of the Moon's age that range as old as the age of the solar system at 4.568 billion years. The new, younger age obtained for the oldest lunar crust is similar to ages obtained for the oldest terrestrial(地球的,陆地的) minerals--zircons from western Australia--suggesting that the oldest crusts on both Earth and Moon formed at approximately the same time, and that this time dates from shortly after the giant impact.

This study is the first in which a single sample of FAN yielded consistent ages from multiple isotope9 dating techniques. This result strongly suggests that these ages pinpoint11 the time at which the sample crystallized.

"The extraordinarily12 young age of this lunar sample either means that the Moon solidified significantly later than previous estimates, or that we need to change our entire understanding of the Moon's geochemical history," Carlson said.

Funding for this work was provided by the Department of Energy, and portions of the work were supported by the NASA Cosmochemistry(宇宙化学) Program.


1 previously bkzzzC     
  • The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • Let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
2 prevailing E1ozF     
  • She wears a fashionable hair style prevailing in the city.她的发型是这个城市流行的款式。
  • This reflects attitudes and values prevailing in society.这反映了社会上盛行的态度和价值观。
3 sufficiently 0htzMB     
  • It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。
  • The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。
4 solidified ec92c58adafe8f3291136b615a7bae5b     
(使)成为固体,(使)变硬,(使)变得坚固( solidify的过去式和过去分词 ); 使团结一致; 充实,巩固; 具体化
  • Her attitudes solidified through privilege and habit. 由于特权和习惯使然,她的看法变得越来越难以改变。
  • When threatened, he fires spheres of solidified air from his launcher! 当危险来临,他就会发射它的弹药!
5 components 4725dcf446a342f1473a8228e42dfa48     
(机器、设备等的)构成要素,零件,成分; 成分( component的名词复数 ); [物理化学]组分; [数学]分量; (混合物的)组成部分
  • the components of a machine 机器部件
  • Our chemistry teacher often reduces a compound to its components in lab. 在实验室中化学老师常把化合物分解为各种成分。
6 derived 6cddb7353e699051a384686b6b3ff1e2     
vi.起源;由来;衍生;导出v.得到( derive的过去式和过去分词 );(从…中)得到获得;源于;(从…中)提取
  • Many English words are derived from Latin and Greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
  • He derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》
7 magnetism zkxyW     
  • We know about magnetism by the way magnets act.我们通过磁铁的作用知道磁性是怎么一回事。
  • His success showed his magnetism of courage and devotion.他的成功表现了他的胆量和热诚的魅力。
8 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
  • The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
9 isotope isotope     
  • The isotope ratio is directly used for comparing oils or gases.同位素比率直接用于比较各种石油或天然气。
  • How to apply a radio isotope?如何运用放射性同位素?
10 isotopes 92848c3160703e48dc3b552ac6f54115     
n.同位素;同位素( isotope的名词复数 )
  • the many isotopes of carbon 碳的诸多同位素
  • Tritium is one of the mildest radioactive isotopes. 氚是最和缓的放射性同位素之一。 来自《简明英汉词典》
11 pinpoint xNExL     
  • It is difficult to pinpoint when water problems of the modern age began.很难准确地指出,现代用水的问题是什么时候出现的。
  • I could pinpoint his precise location on a map.我能在地图上指明他的准确位置。
12 extraordinarily Vlwxw     
  • She is an extraordinarily beautiful girl.她是个美丽非凡的姑娘。
  • The sea was extraordinarily calm that morning.那天清晨,大海出奇地宁静。
TAG标签: moon earth space