When the sun rose over Russia's Ural Mountains on Friday, Feb. 15th,

2月15日星期五，當太陽從俄羅斯'烏拉爾山脈升起時。

many residents of nearby Chelyabinsk already knew that a space rock was coming.

車里雅賓斯克附近的許多居民已經知道，一塊太空石即將到來。

Later that day, an asteroid named 2012 DA14 would pass by

當天晚些時候，一顆名為2012 DA14的小行星將經過：

Earth only 17,200 miles above Indonesia.

地球離印度尼西亞只有17200英里

There was no danger of a collision, NASA assured the public.

美國宇航局向公眾保證，沒有發生碰撞的危險。

Maybe that's why, when the morning sky lit up with a second sun

也許這就是為什麼，當清晨的天空亮起第二個太陽的時候

and a shock wave shattered windows in hundreds of buildings around Chelyabinsk,

和衝擊波擊碎了車里雅賓斯克周圍數百棟建築的窗戶。

only a few people picking themselves off the ground figured it out right away.

只有少數人把自己從地上撿起來，馬上就想通了。

This was not a crashing plane or a rocket attack.

這不是一架墜毀的飛機，也不是火箭襲擊。

"It was a meteor strike--the most powerful since the Tunguska event of 1908,"

`quot;這是一次流星撞擊--自1908年通古斯卡事件以來最強大的一次，`quot。

says Bill Cooke of NASA's Meteoroid Environment Office.

美國宇航局'流星體環境辦公室的比爾-庫克說。

In a one in a million coincidence that still has NASA experts shaking their heads,

百萬分之一的巧合，至今仍讓NASA的專家們搖頭。

a small asteroid completely unrelated to 2012 DA14

隕石星

struck Earth only hours before the publicized event.

在公開的事件發生前幾個小時才撞擊地球。

"These are rare events and it is incredible to see them happening on the same day,"

"這些都是罕見的事件，看到它們在同一天發生是不可思議的，&quot。

says Paul Chodas of NASA's near-Earth Object Program at JPL.

JPL的NASA'近地天體項目的Paul Chodas說。

Researchers have since pieced together what happened.

研究人員後來拼湊出了事情的經過。

The most telling information came from a network of infrasound sensors

最有說服力的資訊來自於一個次聲波傳感器網絡。

operated by the Comprehensive Test Ban Treaty Organization.

由全面禁止試驗條約組織運作。

Their purpose is to monitor nuclear explosions.

其目的是監測核爆炸。

Infrasound is a type of very low-frequency sound wave that only

次聲波是一種非常低頻的聲波，只有

elephants, homing pigeons and a few other animals can hear.

大象、家鴿和其他一些動物都能聽到。

It turns out that meteors entering Earth's atmosphere cause ripples of infrasound

原來，流星進入地球大氣層後，會引起次聲波的漣漪。

to spread through the air of our planet.

在我們星球的空氣中傳播。

By analyzing infrasound records, it is possible to learn

通過對次聲波記錄的分析，可以得知

how long a meteor was in the air, which direction it traveled,

流星在空中停留了多長時間，流星的行進方向。

and how much energy it unleashed.

以及它所釋放的能量有多大。

The Russian's meteor infrasound signal was detected by multiple stations,

俄羅斯'的流星次聲波信號被多個站點探測到。

including one in Alaska more than 6500 km from Chelyabinsk.

包括在阿拉斯加的一個，距離車里雅賓斯克6500多公里。

Western Ontario Professor of Physics Peter Brown analyzed the data:

西安大略省物理學教授彼得-布朗分析了這些數據。

"The asteroid was about 17 meters in diameter

"這顆小行星直徑約17米。

and weighed approximately 10,000 metric tons," he reports.

並重約10,000公噸，"他報告說。

"It struck Earth's atmosphere at 40,000 mph

它以每小時4萬英里的速度撞擊著地球的大氣層。

and broke apart about 12 to 15 miles above Earth's surface.

並在離地球表面約12至15英里處碎裂開來'。

The energy of the resulting explosion exceeded 470 kilotons of TNT."

由此產生的爆炸能量超過470千噸TNT.&quot。

For comparison, the first atomic bombs produced only 15 to 20 kilotons.

相比之下，第一顆原子彈的產量只有15到20千噸。

Based on the trajectory of the fireball, analysts have also plotted its orbit.

根據火球的運行軌跡，分析人員還繪製了它的運行軌跡。

"It originally came from the asteroid belt,

"它最初來自小行星帶。

about 2.5 times farther from the sun than Earth," says Cooke.

距離太陽約2.5倍，比地球遠，"庫克說。

Comparing the orbit of the Russian meteor to that of 2012 DA14,

將俄羅斯流星的軌道與2012 DA14的軌道進行比較。

NASA orbit analysts have shown that there is no connection between the two.

美國宇航局軌道分析人員表明，兩者之間沒有任何聯繫。

"These are independent objects," Cooke says.

"這些都是獨立的對象，"庫克說。

"The fact that they reached Earth on the same day,

"事實上，他們在同一天到達地球。

one just a little closer than the other, appears to be a complete coincidence."

一個只比另一個近一點，似乎完全是個巧合.&quot。

Infrasound records confirm that the meteor entered the atmosphere

聲波記錄證實，該隕石進入大氣層。

at a shallow angle of about 20 degrees and lasted more than 30 seconds before it exploded.

以約20度的淺角，持續30多秒後爆炸。

The loud report, which was heard and felt for hundreds of miles,

那響亮的報告，方圓數百里都能聽到和感受到。

marked the beginning of a scientific scavenger hunt.

標誌著科學尋寶活動的開始。

Thousands of fragments of the meteor are now scattered across the Ural countryside,

數千塊隕石碎片現在散落在烏拉爾鄉村。

and a small fraction have already been found.

並已發現一小部分。

Preliminary reports, mainly communicated through the media,

初步報告，主要通過媒體傳達。

suggest that the asteroid was made mostly of stone with a bit of iron

表明這顆小行星主要是由石頭製成的，還含有一點鐵質

"in other words, a typical asteroid from beyond the orbit of Mars," says Cooke.

"換句話說，這是一顆來自火星軌道之外的典型小行星，"庫克說。

"There are millions more just like it."

"還有幾百萬個這樣的人。

And that is something to think about as the cleanup in Chelyabinsk continues.

而這也是值得思考的，因為車里雅賓斯克的清理工作還在繼續。

For more news about things coming out of the blue, visit science.nasa.gov

更多關於突發事件的新聞，請訪問science.nasa.gov。