66 million years ago, a much larger object hit the Earth, causing a massive extinction. 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。 75 percent of plant and animal species were lost, including, sadly, the dinosaurs.
I am holding something remarkably old. It is older than any human artifact, 我拿着的是一个十分古老的东西。它比任何一个人工制品都要古老， older than life on Earth, older than the continents and the oceans between them. 比地球上的生命古老，也比
Much of this work is funded by NASA. I think of the search for these asteroids as a giant public works project, NASA支持着绝大部分该方面的工作。我把搜寻这些小行星看作一项大型公众项目， but instead of building a highway, we're charting
One of the reasons NEOWISE is so valuable is that it sees the sky in the thermal infrared. 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。 That means that instead of seeing the sunlight that asteroids reflect, NEOWI
