I just saw a headline that said something like “New evidence from Charon reveals Plutos Violent Past” and I thought “What a strange way of putting it?” It’s not as if I have any better suggestions, if I were writing science articles for a major website, I’d probably talk about various planets and their “violent past” too, but it sounds wrong.
When I hear “violent past” I think of a teenage kid who carried a knife, a guy who used to get drunk and get in fights in bars a lot. Planets are large objects which sometimes get hit by other large objects. They are not sentient, so they don’t think of it as violent. It’s the norm, not the exception, so in the culture of planets, it’s very hard to single out a specific one and say “it had a violent past. You should watch out for that one.”
Actually, Earth is probably somewhat blessed in that respect. Although we had a violent past, that stage was billions of years ago. The last world-changing cosmic event was 65 million years ago, and that’s probably about average.
Of course, a couple of contributing factors are the existence of Jupiter, a huge big brother of a planet that the Earth manages to hide behind when some of the worst asteroids are coming in, and the fact that we have an atmosphere, which burns up most of the incoming comets.
So, adding in the L (length of time necessary for a species to evolve and develop a technological civilization) factor to the Drake equation, we may well be one of the lucky very few planets in the Universe to get as far as we’ve got.
And we don’t know how long we can keep it going.