Some scientists believe the water on the earth was brought here by comets.
有些科学家认为地球上水是由彗星带来的。
Some scientists believe the water on the earth was brought here by comets.
地球上的生命源自陨石或彗星带来的分子吗？
2262 - Planets gradually changing planetary orbit. Mars is threatened by comets.
2262年，行星们逐渐转变了自己的旋转轨道，火星被彗星威胁。
The work suggests much of Earth's water could have been brought to the planet by comets.
这项工作表明，目前地球上大部分的水都可能是彗星带来的。
A: The Earth has always been subject to impacts by comets and asteroids, although big hits are very rare.
答：地球一直受到冲击，慧星和小行星，虽然金矿是非常罕见的。
Until rather recently, the prevailing wisdom has been that Earth's water supply was primarily deposited by comets.
现在主流的学者认为，地球上的水来自彗星撞击后的沉淀物。
Consequently, MIPS allows astronomers to study the production of meteoroids by comets whose orbits do not cross the Earth's path.
因此，MIPS使天文学家得以研究与地球轨道不交汇的彗星产生的流星体。
Comet Hartley 2 has the same deuterium-to-hydrogen ratio as ocean water, lending support to the idea that Earth's water was delivered by comets. John Matson reports.
哈特利2号彗星拥有和地球海水相同的氘氢比例，有力支持了地球上的水源于彗星(的观点)。来自约翰·马特森的报道。
Their study could support evidence that water persists in shadowed craters on the moon's surface - and that the water could be native to the moon and not carried there by comets.
这项研究有可能证明在遮蔽在阴影中的月球坑中还有水存在，即“月球上可能原本就有水存在”，否定了月球水来自彗星的说法。
When water lands in sunny spots, perhaps carried by comets or asteroids, the water transforms directly into gas; if it lands in shadow, the water freezes and can remain indefinitely.
当彗星或者其他小行星携带的水着陆在阳光明媚的坑点时，水直接气化。如果落在背阴一面，水就会结冰，不清楚什么时候解冻。
Similarly, there are myriad ways that planets can lose their atmospheres, through stripping by the solar wind, baking by the sun's radiation or catastrophic impacts by comets or asteroids.
同样的，星球也有无数的方法能够丧失自己的大气层，有可能被太阳风夺走，还有可能被太阳的放射性物质或者来自彗星和小行星灾难性的撞击耗尽。
Let's continue our discussion now by talking about orbits, especially those of the so-called periodic-orbit comets.
现在我们继续讨论，谈谈轨道，特别是那些所谓的周期轨道彗星。
It will defend the earth's magnetosphere by deflecting meteorites and comets, it will lessen the effects of gamma rays into the Earth's atmosphere.
它会通过使陨石和彗星偏离而保护地磁圈，这会有效地减少进入地球的伽马射线。
The scientists have analysed the comets in the Oort cloud and deduced that 25 per-cent of them would need a nudge by a body of at least Jupiter size before they changed orbit.
科学家已经分析了奥特云中的彗星，并得出推论称，其中25%的彗星在它们改变运行轨道前，需要至少木星大小的星体提供推动力。
The observations are by no means conclusive, and Lisse concedes that instead of a storm of smallish comets, he could be seeing the debris from a single big one.
这一观测结果还不足下定结论，Lisse承认除了由小彗星组成的“风暴”，他也观测到一个大体积星体的残迹。
Most moons with irregular orbits are thought to be former comets or asteroids captured by their parent planet's gravity, and that may be Nereid's story too.
大多数有着不规则轨道的卫星被认为是被恒星的重力所吸引住的彗星或者小行星，并且海卫二可能也是这样的。
Thousands of near-Earth objects (asteroids and comets) will have been analyzed by telescopes on the Moon and by spacecraft that were launched from the Moon.
将通过设在月球的天文望远镜和由月球发射的宇宙飞船，对数以千计的近地目标星体（小行星和彗星）进行分析研究。
Comets, by contrast, are relatively pristine - at least, below their outer crust.
相比之下，彗星则相对原始——至少在它们的外壳之下是原始的。
For centuries, scientists thought comets traveled in the Earth's atmosphere, but in 1577, observations made by Danish astronomer Tycho Brahe revealed they actually traveled far beyond the moon.
几个世纪以来，科学家一直认为彗星是在地球大气层内运行。但是在1577年，由丹麦天文学家第谷·布拉赫进行的观测揭示出，彗星实际上运行在比月亮还远的地方。
In Earth's formative years, it was hit by thousands of comets like this.
在地球的最初岁月中，它曾被成千上万个这样的彗星撞击。
Epsilon eri is also known to be surrounded by a disk of dust, which may be derived from collisions between asteroids and comets, which is an indirect argument for smaller planets also being present.
我们还知道EpsilonEri环绕着一圈尘埃，可能产生于小行星和彗星之间的撞击，这也是存在更小的行星的一个间接证据。
Note: Since astronomers have not fully understood the mechanism account for the brightening of comets, they can only predict by referring to past comets.
注：由于天文学家还未完全掌握彗星增光的机制，因此只能参考过去其他彗星的情况作出预报。
Icy objects such as comets may have helped start life on Earth by delivering water and carbon-based molecules to the young planet.
像彗星这样的冰状天体曾给年轻的地球提供水和碳基分子，从而促进了地球上生命的起源。
Transient changeable phenomena like comets and meteors could be dealt with simply by assuming that they were atmospheric phenomena, taking place below the sphere of the Moon.
譬如彗星流星此类瞬时变化的现象就只能被认作发生在月球之下的大气现象。
Newly discovered comets are now named after the famous figures proposed by the discoverers.
新发现的彗星是以其发现者的所推荐的名人的名字来命名的。
Newly discovered comets are now named after the famous figures proposed by the discoverers.
新发现的彗星是以其发现者的所推荐的名人的名字来命名的。
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