It is very rare to see a curve on the comets' path.
弧型的彗星轨迹是非常罕见的。
The comets' offspring, the meteor swarms, travel in regular orbits, similar to the earth's orbit around the sun.
彗星的后裔，即流星团，沿正常的轨道运行，与地球绕太阳运行的轨道相似。
They found deuterium at higher levels than it's found in Earth water-but at levels similar to the comets Hale-Bopp, Hyakutake and Halley.
数据显示月球水比地球水包含更多的重氢元素，并与海尔·波普彗星、百武彗星及哈雷彗星更为接近。
They found deuterium at higher levels than it's found in Earth water —but at levels similar to the comets Hale-Bopp, Hyakutake and Halley.
他们发现，同地球上的水相比，氘的含量更高——但同海尔·波普彗星、哈库塔克彗星和哈雷上的水有着相似的平。
They found deuterium at higher levels than it's found in Earth water - but at levels similar to the comets Hale-Bopp, Hyakutake and Halley.
他们发现，同地球上的水相比，氘的含量更高——但同海尔·波普彗星、哈库塔克彗星和哈雷上的水有着相似的平。
DMA damage were detected by single-cell gel electrophoresis assay. After exposure the relative tail length of the comets and cells with DNA migration were increased.
采用单细胞凝胶电泳检测小鼠睾丸细胞DNA受损程度，显示DNA迁移细胞数和彗尾长度上升。
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 Oort cloud is a vast belt of dust and ice that is believed to lie around one light year from the Sun and is the origin of many of the comets that pass through our solar system.
奥尔特云是一个由粉尘和冰组成的庞大云带，据信它距离太阳约一光年，许多穿越我们太阳系的彗星都来自那里。
Thee Oort cloud is a vast belt of dust and ice that is believed to lie around one light year from the Sun and is the origin of many of the comets that pass through our solar system.
奥尔特云是一个由粉尘和冰组成的庞大云带，据信它距离太阳约一光年，许多穿越我们太阳系的彗星都来自那里。
The solar system also has two analogous classes of objects, smaller than planets—namely, asteroids and comets.
太阳系也有两类类似的物体，比行星还小——即小行星和彗星。
The Sun is the hub of a huge rotating system consisting of nine planets, their satellites, and numerous small bodies, including asteroids, comets, and meteoroids.
太阳是一个巨大的旋转系统的中心，这个旋转系统由九大行星、它们的卫星和无数的小天体组成，包括小行星、彗星和流星体。
Roids are, for the most part anyway, they are just smaller bits of asteroids and comets.
在很大程度上，Roids只是小行星和彗星的小碎片。
Second, Jupiter's enormous mass prevents most Sun-bound comets from penetrating the inner solar system.
其次，木星的巨大质量阻止了大多数与太阳结合的彗星穿透太阳系内部。
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。
We think meteors that crashed into the moon or tails of passing comets may have introduced water molecules.
我们认为，撞击月球的流星或经过的彗星尾巴可能会留下一些水分子。
In any given year, about a dozen known comets come close to the sun in their orbits, the average person can't see them all, of course.
在任何一年中，大约有十几颗已知的彗星在其轨道中接近太阳。当然，一般人看不到所有的彗星。
About the same time, though, scientists realized comets might contain decaying radioactive isotopes that could have warmed cometary interiors to temperatures that caused the interiors to evolve.
然而，大约在同一时间，科学家们意识到彗星可能含有衰变的放射性同位素，这些同位素可能使彗星内部的温度升高到导致内部进化的温度。
Comets were formed around the same time the Earth was formed.
彗星与地球大约同时形成。
Comets are similar in composition to the gas giants.
彗星在组成上与气态巨行星相似。
Soaring through the moonlight with Ellen in his arms, the pair of them shooting like comets into eternity while the clock in the parlor stops.
抱着埃伦在月光中飞翔，他们像彗星一样射入永恒，客厅里的钟停了。
Once in deep space, it went though the same process of aggregating into comets.
进入外太空后，彗星形成的过程就和以前所知并无二致了。
On first blush, you might think not: the planet where the comet or comets came to grief is farther out than Mars, in an orbit where water would be permanently frozen.
一开始你可能不会这样认为，因为太阳系里和彗星发生过碰撞的行星都比火星还远，在那样的轨道上水永远是以冰的形式存在。
Other particles within the disk collided and stuck together to form asteroid-sized objects named as planetesimals, some of which combined to become the asteroids, comets, moons and planets.
其它在盘状星云中的物质相互碰撞合并，形成小行星尺寸的星体，称为“星子”，一些星子相互结合，形成小行星、彗星、卫星和行星。
This discovery led to the belief that comets supplied the moon with a majority of its water back when it originally formed.
这一发现产生了一个信念- - - - - -远在月球最初形成时，彗星给月球提供了大部分的水。
Asteroids classify comets based on the durations of their orbits around the sun.
天文学上把彗星按照它们的轨道周期分类。
While comets supplied the moon's internal supply of water, solar winds supplied the moon's external supply of water.
彗星提供月球的内部供水，而太阳风提供月球的外部供水。
Taylor and his team believe the water came from comets crashing into the moon shortly after it formed.
泰勒和他的小组相信水是在月球形成之后不久，撞到月球的彗星带到月球上去的。
The idea isn't that these building blocks are just passengers aboard meteorites, but that the chemistry inside asteroids and comets can actually manufacture the essential building blocks of biology.
该想法并不是认为这些结构单元只是搭乘陨石的乘客，而是小行星和彗星中的化学成分实际上可以制造生物的结构单元。
The big planet throws a lot of comets out of the solar system, but it also throws them in.
这个大魔头向太阳系外扔了很多扫帚星，但又把它们引向了太阳系内部。
The big planet throws a lot of comets out of the solar system, but it also throws them in.
这个大魔头向太阳系外扔了很多扫帚星，但又把它们引向了太阳系内部。
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