▽Astronomy Picture of the Day ●04/28 11:55 2021 October 12 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 brighter than any planet -- as well as bright