What are the Leonids?狮子座流星群

时间：2007-01-30 07:17:47

（单词翻译:单击）

What are the Leonids?
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Every year in mid-November, Earth passes close to an area of the debris¹ trail left from the passing of periodic comet Tempel-Tuttle. The trail is littered with very small sand grain sized pebbles² and dust that have been eroded³ off the comet by the solar wind and radiation. As Earth collides with this trail of dust every year, we usually can observe a meteor shower with some 15 to 20 meteors visible per hour.

Comet Tempel-Tuttle orbits the sun once every 33 years. When the comet is close to the sun, it comes close to Earth's orbit replenishing the vicinity with fresh meteoric⁴ debris. It is just after this comet passes close to Earth's orbit, as it did in 1999, that we have a higher probability of a meteor storm. Fortunately, the comet crosses Earth's path when the Earth is on the other side of the sun so there is no chance the comet slamming into Earth.

As pieces of this cometary debris enter Earth's atmosphere at an extremely high rate of speed, they sometimes cause the atmosphere to glow along their path leaving a visible ionized meteor trail. As Leonid meteors appear to emanate⁵ from, or point back to, the constellation⁶ Leo, it is known as the annual Leonid Meteor Shower.

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Leonid
n.狮子座流星群
Leonid Meteor Shower
狮子座流星雨

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1 debris
n.瓦砾堆，废墟，碎片
参考例句：
After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。 Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上，导致蛀牙。

2 pebbles
[复数]鹅卵石；沙砾；卵石，小圆石( pebble的名词复数 )
参考例句：
The pebbles of the drive crunched under his feet. 汽车道上的小石子在他脚底下喀嚓作响。 Line the pots with pebbles to ensure good drainage. 在罐子里铺一层鹅卵石，以确保排水良好。

3 eroded
adj. 被侵蚀的，有蚀痕的动词erode的过去式和过去分词形式
参考例句：
The cliff face has been steadily eroded by the sea. 峭壁表面逐渐被海水侵蚀。 The stream eroded a channel in the solid rock. 小溪在硬石中侵蚀成一条水道。

4 meteoric
adj.流星的，转瞬即逝的，突然的
参考例句：
In my mind,losing weight is just something meteoric.在我眼中，减肥不过是昙花一现的事情。 His early career had been meteoric.他的早期生涯平步青云。

5 emanate
v.发自，来自，出自
参考例句：
Waves emanate from the same atom source.波是由同一原子辐射的。 These chemicals can emanate certain poisonous gases.这些化学药品会散发出某些有毒的气味。

6 constellation
n.星座n.灿烂的一群
参考例句：
A constellation is a pattern of stars as seen from the earth. 一个星座只是从地球上看到的某些恒星的一种样子。 The Big Dipper is not by itself a constellation. 北斗七星本身不是一个星座。