translation.en: There are about 100,000 balls of ice and rock -- comets, really -- out there, that are 50 miles in diameter or more, and they regularly take a little spin, in towards the Sun and pass reasonably close to us.
translation.zh: 那里堆积了约10万个冰封的石头——实际上就是彗星 直径均为50英里或更大， 规律地面朝太阳旋转着 并合理的从地球旁驶过。