The comet, if that is what caused it, did not actually graze the planet, it grazed the Earth's stratosphere and due to the high speed of this comment, the energetic force created by the friction between the cosmic body and the air hit the ground provoking the explosion. However, do keep in mind that this is just a theory.

Avid Writer with invaluable knowledge in Business Studies, History and Psychology. “You make your own life”