How big of a hole does it take to worry you?

I have been away for too long.  My excuse is that I experienced a turkey-induced food coma, and with all the turkey leftovers it lasted quite a while.  That is my story and I am sticking with it!

Let's get on with the search for the big holes, the ones from the truly scary rocks.  

The name is Chicxulub.  It sounds exotic.  Chicxulub is not a high-dollar, trendy resort frequented by equally high-dollar, trendy people.  Chicxulub is not a vacation destination, but it is tropical.  Chicxulub is straight south of New Orleans across the Gulf of Mexico, and a little over 300 kilometers west of Cancun.  Once upon a time, more than just a few years ago, the place that would become known as Chicxulub was a scene of unimaginable destruction.  We do not know if the day was sunny or overcast, indeed we do not know if it was daytime at all.  There were no people around to witness the event; that is a good thing, because most of the life on this planet was probably snuffed out.  An asteroid approximately 10 kilometers in diameter slammed into our lovely planet.  (Just to get an idea of the size of this thing, at the instant the asteroid first touched the surface of the Earth, the other side of the asteroid was just about at the cruising altitude of our airliners.)  The ground splashed, like a mud puddle when a child throws a pebble into it.  Uncountable tons of rock and dust was blasted into the upper atmosphere.  Hot debris rained down world-wide, and estimates as high as ninety percent of the world’s biomass burned.  Some of the biggest megatsunamis this poor planet has ever seen resulted from the impact; some of them were perhaps a half a mile high.  The blast yield of this impact has been estimated to exceed 100 million megatons.  The shock likely triggered earthquakes around the world, as well as extensive volcanic activity.  The dust and other debris in the atmosphere would have lingered for years, blocking out sunlight and therefore putting a halt to plant life.  The resulting crater (as measured today) is more than 180 kilometers across.  This little party is referred to as the K/T event; it ended the Cretaceous Period and began the Tertiary Period.  (There is still some debate whether the Chicxulub impact killed off the dinosaurs or not.  However, even some of the critics of asteroid as dino-killer theory accept it as a contributor to their demise.)

Are there even bigger holes?  Well, yes.  There are, although there are not many and they are not a great deal bigger.   Are we likely to experience a similar event?  Eventually, with certainty.   Soon, almost certainly not.  However, we do not need to be threatened with the sterilization of our planet to have a very bad day.

I am almost through talking about party-crashers.  I do want to mention a rather unsavory neighbor that paid us a fleeting visit fairly recently, and has promised to come back.  I will deal with that topic next time.