谁才是"地球终结者"?

EarthSky

Many scientists believe that – more than 60 million years ago – an asteroid six miles wide struck in Mexico's Yucatan and triggered the end of the dinosaurs. EarthSky spoke with astrophysicist David Helfand of Columbia University on the risk to people today from killer asteroids.

许多科学家相信,6千万年前一个宽6英里的小行星撞击墨西哥尤卡坦半岛是导致恐龙灭绝的原因。这些小行星是否会对人类生存造成潜在威胁呢？栏目组就这一问题采访了哥伦比亚大学天体物理学家大卫·赫尔方。
 
David Helfand: The very big ones, the ones that have global consequences, such as the one 64 million years ago that killed the dinosaurs, are very rare. They hit the Earth roughly every hundred million years or so.

大卫·赫尔方：那种能带来全球影响的，类似于6400万年前造成恐龙灭绝的巨型小行星实际上很少。行星撞地球这种事每隔一亿年左右才会发生一次。
 
Dr. Helfand said that scientists today are tracking large space rocks that are potentially hazardous.

赫尔方博士称目前科学家正着手追踪那些能给地球带来潜在威胁的大型太空岩石。

David Helfand: Right now, the survey is pretty complete for objects larger than a kilometer in size. Helfand added that tracking an asteroid is just the first step. The next step is prevention of a collision with Earth.

大卫·赫尔方：目前就大小超过一千米的星际物质的有关调查已接近尾声。赫尔方接着补充道，追踪小行星只是调查的第一步。接下来要做的就是阻止它们撞地球。

David Helfand: Several ideas have been proposed: throwing up nuclear weapons at them, throwing at the satellite that gravitationally tugs its way a little bit, so its orbit changes ever so slightly just enough to miss the Earth as it whizzes past.

大卫·赫尔方：人们提出了好几种方案，比如发射核武撞击小行星，或者利用人造卫星的引力使小行星轨道发生轻微偏移，这样就能保证它们高速掠过时只是与地球“擦肩而过”而不会撞上。
 
In 2029, asteroid Apophis – about the size of a football stadium – will whisk closely past Earth. Scientists are confident it will miss, but Helfand said Apophis is a good reminder that killer asteroids are out there.

足球场大小的小行星“阿波菲斯”将于2029年“光顾地球”。科学家们确信它不会与地球相撞。但赫尔方指出，“阿波菲斯”是个很好的例子，它提醒人们注意“杀手行星”的存在。