There is an asteroid on a collision course with the Earth.
有个小行星正处于可能与地球发生碰撞的航向上。
Scientists were debating whether an asteroid was about to hit the Earth.
科学家们在争论一颗小行星是否要撞上地球。
The largest asteroid is Ceres, which is about a quarter the size of the moon.
最大的小行星是谷神星，其体积大约是月球的四分之一。
Will an asteroid hit the Earth?
会不会发生小行星撞击地球的事件呢？
Some of them could even become the first to visit an asteroid.
他们中的一些甚至可能第一个访问小行星。
You can find large diamonds in the asteroid belt.
你可以在小行星带找到巨型钻石。
This is the first asteroid sample return mission.
这是首个收集小行星样本的任务。
That means they most likely came from an asteroid.
这意味着它们最有可能来自一颗小行星。
Large meteorites actually come from the asteroid belt.
大型陨星实际上是来自小行星带。
But he wanted to locate the impact site of the asteroid.
但是他想确定小行星的撞击地点。
But…it has entered an asteroid field and we cannot risk…
他们进到小行星群，但…我们不敢冒险前往…
Sometimes an asteroid will leave that path and hit Earth.
有时某个小行星会脱离这条轨道，并撞向地球。
Potential destinations include an asteroid, the moon and eventually Mars.
现在以确定的潜在目的地有小行星，月球，当然最终自然是火星。
Astronomers have yet to witness an asteroid impact with another planet.
天文学家还没有目击过小行星撞击其它行星。
An asteroid, the size of nine ocean liners will pass close to earth today.
今天，一颗体积相当于9艘远洋邮轮的小行星将接近地球。
The asteroid was first spotted during a routine survey performed by a satellite.
这颗小行星是在一次例行检查中被一颗卫星发现的。
About halfway through that period, known as the Triassic, an asteroid struck Earth.
在那段时期的中间，也就是三叠纪时期，一颗小行星撞击了地球。
But until now, no such asteroid-asteroid collision has been caught "in the act".
但是，直到今天，我们都没有“当场”捕捉到这种小行星对小行星的碰撞。
An unmanned American spacecraft has made the first ever landing on an asteroid.
一艘美国无人驾驶探测器在一个小行星上首次着陆。
The asteroid is the smooth spherical uniform ball with constant surface albedo.
设小行星是个光滑的规则圆球，表面返照率不变。
It's very unlikely that an asteroid will crash into Earth but the danger exists.
小行星撞地球的可能性很小，但这样的危险还是存在的。
The asteroid was first spotted during a routine survey performed by a satellite.
这颗小行星是在一次卫星的例行检查中被首次发现的。
This one is the asteroid ida. note its little moon satellite, dactyl , at the right.
这是小行星依达，右方的小白点为其卫星达克图。
Instead, the pass gives astronomers a rare opportunity to study the asteroid in detail.
相反，这次通过给了天文学家详细研究小行星的一个难得机会。
我们能不能让小行星停止运行？
"Asteroid strike?" said Aziraphale.
“小行星撞击？”亚茨拉菲尔说。
"Asteroid strike?" said Aziraphale.
“小行星撞击？”亚茨拉菲尔说。
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