comets

Perhaps, extinctions are caused by something outside, like comets and asteroids.

也许, 灭绝是由外来物体引起的, 比如彗星和小行星.

Specifically, the ratio of heavy hydrogen, or deuterium, to regular hydrogen was too high in the comets.

具体而言，在彗星中，重氢，或者说是氘以及氢的含量更高。

Did life on the earth originate from molecules deposited by meteorites or comets?

地球上的生命源自陨石或彗星带来的分子 吗 ?

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。

In addition, there are thousands of small bodies as asteroids and comets.

此外, 被发现的还有成千上万的小型天体像是小行星和彗星.

Most stars probably have their quota of planets, meteorids, comets, and asteroids.

多数恒星也许还拥有若干行星 、 流星 、 彗星和小行星.

Any school kid can tell you that comets are made of ice.

随便找个小学生都会告诉你,彗星是由冰组成的.

As comets go, it is a whopper.

就彗星而言，它可是个庞然大物。

SCIENCE On the Scientific Objective of Space Exploration to Comets

论彗星空间探测的科学目标

The many impact craters that have and Earth reveal our solar system can be like a shooting gallery, with asteroids and comets regularly striking planets and their companions.

众多撞击留下的深坑让我们的地球和月球表面坑坑洼洼，他们在向我们揭示，太阳系可能是个射击场，小星星和彗星像横飞的子弹一样不断地撞击着行星和他们的卫星。

Stellar passings can perturb the orbits of comets.

行星的运行会使彗星的轨道发生扰动.

Like his peers, geophysicist Steven Jacobsen from Northwestern University believed that water on Earth originated from comets.

美国西北大学地球物理学家史蒂文雅各布森曾认为，地球上的水源于彗星。

They were stars, I knew, and flaring comets, that peopled my flight among the suns.

我知道是这些星辰和闪烁的慧星遍布在我飞行恒星之间的航程中.

These small objects, including asteroids, Kuiper Belt objects, comets and interstellar dust.

这些小天体包括小行星 、 柯伊伯带的天体 、 彗星和星际尘埃.

The earth crosses the tracks of certain comets.

地球穿过某些彗星的轨迹线.

Prof Tiffany likes to sober up his students by reminding them that, historically, great powers have appeared and faded like comets.

蒂法尼教授喜欢提醒学生：在历史上，大国的出现和消失都如彗星一般，从而让学生们清醒起来。

...unnamed comets and asteroids.

未命名的彗星和小行星

We can see comets only when they come close to the earth.

只有当彗星接近地球时,我们才能看得见它们.

Scientists want to learn how comets come into being.

科学家们想了解彗星是怎么形成的.

Early Studies were connected with the origin of short-period comets.

早期的研究是为了探讨短周期彗星的起源.

We can see comets only when they come close to the earth

come close to接近只有当彗星接近地球时，我们才能看得见它们。

This paper analyses the structure of the outer edge region of the solar nebular disk, and shows that no formation zone of comets can exist there.

本文分析了星云盘外缘区的结构，论证了那里不可能存在彗星形成带。

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。

We need to study more comets.

我们需要研究更多的首星.

Comets are usually made of ice and rock.

彗星通常是由岩石和冰构成的.

The idea overturns previous theories that colliding asteroids2 and comets were a purely3 destructive process with the lunar crust being created by magmas rising from the interior.

这个观点推翻了之前的理论，即小行星和彗星的碰撞纯粹是一种破坏性的过程，以为月壳是由月球内部上升的岩浆形成的。

Comets are probably the most numerous astronomical bodies in the solar system aside from small meteor fragments and the asteroids.

在太阳系中，除流星小碎块和小行星之外，彗星也许可以说是数量最多的天体了。

There are about 800 comets whose orbits are known.

人类已经知道有运行轨道的彗星大约有800颗.

Comets look flashy, but they're not in the same league as the Nimbus.

彗星倒是挺耀眼的，但它们和光轮根本不是一个档次。

The night sky is occasionally host to the transient visitors known as comets and meteors.

夜空有时还接待如彗星和流星那样的过路来访者.