In his book Cosmos, the late scientist Carl Sagan talks aboutthe way in which the earth is regularly struck by material fromouter space.
已故科学家卡尔·萨根在著作《宇宙》中叙述了外太空物体如何有规律和地球发生碰撞。
These collisions with space debris can beminor–as in a shooting star on a summer night–or amazinglydestructive, as in the collision that probably killed off thedinosaurs.
太空垃圾和地球碰撞的机率很小，就像夏夜划过流星，破坏性却很大，这种碰撞可以令恐龙灭绝。
Thankfully, the biggies are extremely rare.
值得庆幸的是，这种机率太渺茫了。
Sagan makes the point that the most dangerous collision facing us now, however, is one thatmight be mistaken for something else:a nuclear attack.
萨根阐述的观点是目前我们面临的最危险的是碰撞而非人们误解的核战。
He warned that thinking an asteroid isactually an ICBM could result in the worst possible destruction–an unintended war.
他提醒人们，事实上，行星就像洲际弹道导弹，可能产生意料外破坏性极大的战争后果。
Was this just paranoid thinking? Unfortunately, no.
这仅仅是偏执思维吗？不幸地是，无独有偶。
Carl Sagan is no longer with us, but intestimony before congress just last year, a United States Air Force brigadier general warned thatjust such a thing almost happened in June of two thousand and two.
去年，一位美过空军准将在国会的一份证词中称类似的事情发生在2002年6月。
That's when a meteoroid entered the earth's atmosphere over the Mediterranean and was picked up by U.S. early-warning satellites on the lookout for high-altitude explosions and incoming missiles.
美国预警卫星在监测高空爆炸物和来袭导弹时发现一颗流星穿破地球大气层，降落在地中海地区。
The alarming object falling from the sky was recognized for what it was, this time.
而这次人们确认从天而降令人惶恐的物体究竟是什么。
The generals'point, though, was that we never know where space junk will fall.
准将指出我们无法确定太空垃圾降落在什么地方。
Turn the globe by just a fewhours earlier on that day in June and the meteoroid would have been over the border of Pakistanand India–exactly where everyone was fearing a nuclear attack.
如果六月的这天，地球转动退回到几小时前，流星降落的地方就正好是巴基斯坦和印度的交界处，世人唯恐发生核战的交界地。
We've been lucky so far.
迄今为止，我们都还很幸运。
But Carl Sagan's warning came perilously close to becoming a prophecy and a harmless natural event in the sky, to triggering a terrible event here on earth.
但是，卡尔·萨根的提醒很可能是可怕的预言，本来平常的天空自然事件很可能引发地球灾难。
