Speaker：Carrie Nugent

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摘要

• These are all of the known near-Earth asteroids, which at last count was 13,733. Each one has been imaged, cataloged and had its path around the Sun determined.
  这些是已知的近地行星，它们的最新统计量为13733。每一个都被拍照，分类并且确定了它绕太阳旋转的轨道。

• Three years ago today, a small asteroid exploded over the city of Chelyabinsk, Russia. That object was about 19 meters across, or about as big as a convenience store. Objects of this size hit the Earth every 50 years or so.
  三年前的今天， 一个小行星在俄罗斯的车里雅宾斯克爆炸。那个东西有19米宽，或者说像一个便利店一样大。像这样大的物体每五十年左右撞击一次地球。

• 66 million years ago, a much larger object hit the Earth, causing a massive extinction. That object was about 10 kilometers across, and 10 kilometers is roughly the cruising altitude of a 747 jet.
  六百六十万年前，一个更大的物体撞击地球，造成了物种大灭绝。那个物体有十千米宽，而十千米是波音747的巡航高度。

• One of the reasons NEOWISE is so valuable is that it sees the sky in the thermal infrared. This is a vital capability since some asteroids are as dark as coal and can be difficult or impossible to spot with other telescopes.
  NEOWISE有这样高价值的原因之一便是它使用红外感应观测天空。这是一项很重要的能力，因为一些小行星像黑碳一样暗，其他的探测器很难或不可能发现这类行星。

• The community, together, discovered over 90 percent of asteroids bigger than one kilometer across -- objects capable of massive destruction to Earth. But the job's not done yet. An object 140 meters or bigger could decimate a medium-sized country.
  参与的组织共同发现直径大于一公里的 百分之九十以上的小行星。这些物体能对地球造成巨大破坏。但是工作并没有结束。一个140米宽或更大的物体能够摧毁一座中型城市。

• If we found a hazardous asteroid with significant early warning, we could nudge it out of the way.
  如果我们发现一个极具危险性的小行星并提前发出有效警告，我们便可以把它推走。