When you watch one of those rather terrifying meteor impact movies, you are always comforted by the prospect that the doughty, resourceful protagonists of these movies usually manage to do just fine after a little bother with the after-effects of their own impacts.
Life goes on as before, albeit with a few real estate assets destroyed and a few people – sometimes more than a few, killed. the sun comes out, the rainbow appears, and life heads back to normality, perhaps not at the previous level, but liveably.
But that is the Pollyanna version of how a major impact event would play out. it makes a nice, comforting movie with just the right amount of titilating anxiety and a happyish ending, but, scientists tell is that the reality would likely be much, much, worse.
There are so many dimensions to this horror that I can only deal, sketchily, with one outline of events at a time.
The first in time would be the physical efffects of the blast. these would be various and devastating on the instant of that blast.
Few of us, mercifully, have any conception of the effects of the effects even that the baby version of such a blast would have – like a multi-megation thermonuclear explosion. Other than tests, no such explosions have been used against any targets that were not isolated and tailored to limit the destuctivness of the bomb, so we really don’t have any idea of how much damage would be caused by even such a relatively puny device.
The Chixulub impact that is said to have killed the Dinosaurs and caused a major extinction, has now been studied quite a bit, and certain facts have been learned about this moderate-sized explosion that left the earth at least able to regenerate itself over about 10,000 years or so.
Because the size of the crater and the characteristics of the target zone have been studied, calculations indicate that the explosion was the equivalent of about 100 million megatons of TNT.
Just to try to put it into perspective, the largest thermonuclear bomb ever exploded was the Tsar Bomba dropped by Russia in the 60’s that had a power of 50 megatons. Its fireball was more than 4 miles wide and the light of the fireball could be seen for 2,000 kilometers. The mushroom cloud from the explosion was more than 65 kilometers high. This is compared to the nominal thickness of the atmosphere of about 100 kilometers.
The Chicxulub impact was a minimum of 2 million times larger than the largest man-made explosion. That is far larger than any of us can imagine. Such an explosion would be a world-encompassing event.
It caused an explosion that released enough energy to superheat material to sunlike temperatures, ripping molecules apart to form plasma like the sun that created a heat wave that incinerated everything it touched for multiple thousands of miles, followed by a shock wave composed of superfast winds that knocked down anything the heat wave didn’t burn away that gradually attenuated, still to blow hurricane force winds for another thousand miles.
After that the mushroom cloud that contained the vacuum stack that briefly extended up into space, the gap formed by the impactor physically pushing aside the air gradually filled in, carrying the molten materials created by the explosion high into the stratosphere. They then rained down on the earth all around the globe and create fires eveywhere they fell.
That was just the first stage of the disaster that was followed by a nuclear winter effect orders of magnitude greater than any effect of the puny nucleart bombs we can create. This winter, because of the amount of material lofted, and the height it was raised to, persisted for decades, perhaps longer, before the sun-blocking particles gradually settled out of the atmosphere. In the meantime, all wildlife and plant life, incuding almost all life in the oceans, would die.
If it happedned to us, I don’t think I need to go on. No need to dwell on the electrical effects that the swirling hot gases in the atmosphere would produce, wiping out the technical infrastructure of our civilization, leaving us defenseless in the face of the worst of disasters with no way to restore our ability to cope.
It would be a bad day for humanity the day that happened. Maybe, as I hope in Moon Life, we would survive, and maybe we wouldn’t. Many of the the pre-existing creatures on our planet did not survive. This happened at least five times that we know of.
Most rational people do not believe that any extinctions could happen to us, but, no-one offers any proof of it, whilst many can offer proof that it has happended to other living systems in the past.
We now have the means to establish a colony on the moon. The moon is close enough, and being tidally locked to the earth, visible almost all the time, to facilitate practical remote operation of drone machinery that can effectively start the necessary work of establishing a moon colony. We also are sure taht the moon contains the resources we would need to survive there.
Then,when the inevitable happens, or even if it does not, we can be sure that we will not disappear from the universe.
Considering that we are the only intelligent technological creatures we know of, I submit that it would be a sin for all the achievments of mankind to disappear, leaving Voyager to be the only evidence of our existence. We owe it to our ancestors.