How many events like the one that killed the dinosaurs (mass extinction events) have there been in the history of earth? Five!
GRB or Asteroid are also ELE that the GP did not mention.
GRB or Asteroid are also ELE that the GP did not mention.
That is, if we assume a GRB intersects Earth, what is the probability that it won't also hit Mars?
Very Big Asteroids are definitely one event it would serve us well for though.
https://en.wikipedia.org/wiki/Gamma-ray_burst#Energetics_and...