13-11-20 For nearly as long as astronomers have been able to observe asteroids（小行星） , a question has gone unanswered: Why do the surfaces of most asteroids appear redder than meteorites（陨石） -- the remnants of asteroids that have crashed to Earth? In...

12-02-13 The giant black hole at the center of the Milky Way may be vaporizing and devouring（吞食，毁灭） asteroids, which could explain the frequent flares observed, according to astronomers using data from NASA's Chandra X-ray Observatory. For several yea...

10-07-17 Life on Earth is wiped out every 27 million years and we have about 16 million years left until the next extinction, according to scientists. 科学家称，地球上的生命每隔2700万年就会被灭绝一次，我们到下一次大灭绝之前还有约1600万年时间。 Research into...