加拿大路易斯湖上空的火流星
2021年10月12日 Fireball over Lake Louise Image Credit & Copyright: Hao Qin Explanation: What makes a meteor a fireball? First of all, everyone agrees that a fireball is an exceptionally bright meteor. Past that, the International Astronomical Union defines a fireball as a meteor brighter than apparent magnitude -4, which corresponds (roughly) to being brig...