�I�竟什么时候能够成为“火星�h“�/h1>

来源９�span>ufo110�U�烦�|?www.fallstig.com)外星������?/a>发布旉���９�span>2011-12-12

我们认�ؓ火星是一个跟地球环境很接�q�的星球。尽���他们在我们太阳�p�里是第三和�W�四的星球，但是地球和火星的行程�q�程可能很不一栗���根据两位科学家现在的估���，地球和火星之间巨大的地理性差异可能是因�ؓ在太阳系形成后，火星的成长史只有短短的二百万到四百万�q��?

In contrast, Earth grew to its full size 50 to 100 million years after the solar system��s birth, via collisions with other small bodies in the solar system.
相反，太阳系形成之后，地球经历了五千万到一亿年，通过无数太阳�p�里���的星体�怺����撞才有了今天的体积、�/p>

Mars��s rapid formation might help explain why it is so small �C the runt of the planetary litter among inner worlds in our solar system �C say the study��s co-authors.
�q�次研究的合作者说，火星的�q�速�Ş成可以解释�ؓ什么它的体�U�那么小的原因，可以�v�它是我们太阳系内的侏儒行星了、�/p>

Nicolas Dauphas at University of Chicago and Ali Pourmand at University of Miami made the suggestion of Mars�� rapid formation in a study published in the May 26, 2011 issue of the journal Nature.
来自芝加哥大学的���古拉斯��道法斯和�q�阿密大学的阉K����布尔曼�d在一���学术论文中提出火星的迅速�Ş成的�v�法。这���论文发表在2011�q?�?6日的《自然》期刊上、�/p>

Hubble Space Telescope took this picture of Mars on June 26, 2001, when Mars was approximately 68 million kilometers (43 million miles) from Earth - the closest Mars has been to Earth since 1988. Image Credit: NASA and ESA
哈勃太空望远镜在2001�q?�?6日拍摄的火星照片，那时候火星远����/p>

地球���近6800万公里（4300万英里），这�?998�q�以来距���d��球最

�q�的一�ơ。图片所有权� NASA和ESA、�/p>

Relative size of the inner planets of the solar system (from l-r): Mercury, Venus, Earth, and Mars. New research supports the idea that Mars owes its small size to its relatively rapid formation. Image Credit: Lunar and Planetary Institute
太阳�p�d��部行星的相对体积（拍�?-r）：水星、金星、地球和火星、�/p>

新的研究支持了火星的体积���是因�ؓ其�������速的形成�q�程的观炏V���/p>

囄���所有权：月球和行星研究所、�/p>

Mercury, Venus, Earth, and Mars are sometimes called the terrestrial planets. In other words, the assumption has been that they are like Earth, formed in a similar way and time. But Mars probably should not be considered terrestrial, or Earthlike, said Dauphas, who is an associate professor in geophysical sciences:

水星、金星、地球和火星通常被称为陆地行星。换�U�说法，我们已经假定他们都像地球了，用��似的方式和在差不多的旉���内�Ş成。但是，火星可能不应�v�被成�ؓ陆地行星，或者类地行星，道法斯如此说道。他是一位地球物理学领域的副教授、�/p>

Earth was made of embryos like Mars, but Mars is a stranded planetary embryo that never collided with other embryos to make an Earthlike planet.
地球是由�c�M��于火星一��L��胚胎�l�成，但是火星是一个被遗忘的行星胚胎，

它从未与别的胚胎相碰撞，从而�Ş成类地行星、�/p>

When he speaks of embryos, he is speaking of bodies that formed within a vast disk of gas and dust �C with the infant sun at its center �C that existed four-and-a-half billion years ago when our solar system was first forming. Planetary embryos are thought of as bodies big enough to have undergone at least some internal melting, so that the interiors of these bodies have begun a process of forming layers. Planetary embryos are believed to form out of kilometer-sized planetesimals that attract each other gravitationally and collide.

当他�v�到胚胎�Ӟ��他是在说在一个充满气体和���埃的巨大磁盘中形成的物体，存在于四十五亿年前太阳系刚刚形成的时候，�q�以�q�年时期的太阳�ؓ它的中心。行星胚胎被认�ؓ是��够大的物体，��n��可以�q�行一些内部融合，于是，这些物体的内部���开始了形成层的�q�程。据信，行星胚胎最�l��Ş成直径达到数公里的小行星，这样就能在�怺�之间产生重力吸引力，最�l���生碰撞、�/p>

According to planet formation theory, there was a process of building that went on in the early solar system �C smaller planetesimals to larger planetary embryos to actual planets. The idea here is that �C while Earth formed slowly from planetary embryos colliding �C Mars is itself a solitary planetary embryo that formed very early in the history of our solar system.#p#副标�?e#

�Ҏ��行星形成理论，在太阳�p�L��期，存在一个�Ş成过�E�，更小的小行星形成�E�大的行星胚胎，最�l��Ş成现在的行星。这里想表达的观�Ҏ��，当地球从行星胚胎间�怺����撞�~�慢形成�Ӟ��火星却是一个孤独的行星胚胎，在太阳�p�d��史上形成得很早、�/p>

The new work provides supporting evidence for this idea, which was first proposed 20 years ago on the basis of planetary growth simulations. The new evidence likely will change the way planetary scientists view Mars. Pourmand, who is an assistant professor in marine geology and geophysics, said:

新的发现�����个观�Ҏ��供了支持�v�据，这个观炚w��先是�?0�q�前的行星成长模拟中提出的。新�v�据可能���会改变行星�U�学家们看待火星的态度。布���曼��h��一位在���h��地质和地球物理方面的副教授，他这么说９�/p>

We thought that there were no embryos in the solar system to study, but when we study Mars, we are studying embryos that eventually made planets like Earth.
我们以前认�ؓ在太阳系，没有胚胎值得�ȝ���IӞ��但是当我们研�I�火星时＋�/p>

我们���是在研�I�最�l��Ş成类似地球的行星胚胎、�/p>

There have been large uncertainties in the formation history of Mars because of the unknown composition of its mantle, the rock layer that underlies the crust. Dauphas said:

因�ؓ其地�q�的未知混合物，火星形成历史上还有诸多不���定因素。地�q�是一个位于地壳下面的岩石层。道法斯�v�道９�/p>

Now we can shrink those uncertainties to the point where we can do interesting science.
现在我们能将�q�些不确定因�y�范围羃���到能开展有���科学实验的�E�度、�/p>

Dauphas and Pourmand were able to refine the age of Mars by using the radioactive decay of the elements hafnium to tungsten in Martian meteorites �C that is, meteorites from the planet Mars that have come to Earth. Read more about Martian meteorites here.

道法斯和布尔曼�d能通过在火星陨石中铪元�y�变成钨元素的放���性衰变过�E�来�_����火星的年�U�。那���是�v�_��曾有火星的陨��n��落到地球。我们在�q�里了解更多的火星陨石信息、�/p>

To read the details of the process by which Dauphas and Pourmand studied radioactivity decay in Martian meteorites �C and arrived at their conclusions �C see a May 25, 2011 press release from University of Chicago.

要了解道法斯和布���曼��L��来研�I�火星陨石的攑ְ�性衰变的�q�个�E�序�l�节，并得出他们的结论，可以�ȝ���?011�q?�?5日芝加哥大学出版�C����刊物、�/p>

Bottom line: Scientists Nicolas Dauphas of the University of Chicago and Ali Pourmand of the University of Miami have conducted a study on the formation of Mars, published in the May 26, 2011 issue of the journal Nature. Their results show that Mars formed in as little as two to four million years after the birth of the solar system. This is more quickly than Earth formed and would explain the small size of Mars. The study was derived from an examination of radioactive decay in elements found in Martian meteorites.

�l�果：芝加哥大学的科学家���古拉斯��道法斯和�q�阿密大学的�U�学安����?middot;布尔曼�d开展了一��关于火星�Ş成的研究，发表在2011�q?�?6日的《自然》杂志上。他们的研究�l�果昄���，火星仅仅�Ş成在太阳�p�dŞ成之后的两百万到四百万年间。这�q�比地球形成要快，并且能解释��Z��么火星体�U�那么小的原因。这个结果来自对火星陨石的元�y�放���性衰变研�I�、�br />