Could earth been hit by an asteriod so massive, that earth history was destroyed?
I got to thinking about this. We can look back at all the previous layers as we dig deeper into the Earth. There are perhaps thousands of recongizable layers. Now, imagine long abo, something impacting the earth that actually hit with such force, it blew off the top 100 or so layers. When the dirt settles, any history of what happed during those last 100 or so layers is completey lost.
The world continues on. Is it possible that we could determined that this ever happened. Again, enough layers are destroyed to completely wipe out thier existance. (kinda makes me wonder if life as complcated as our own could have even been here.
OK, but for all of that to work, the impact has to be massive enough to blow off enough layers of the earth to completely destroy any evidence that those layers were there - WHILE, at the same time, not blow up the earth itself.
Yes, and it has actually happened. The Moon was formed by the impaction of a Mars sized body with the Earth. Enough material was put into orbit to form the moon, and the entire Earth was re-arranged. This was about 4.6 billion years ago. Since then there has never been an impactor large enough to entirely wipe out the geologic record, though subduction and erosion have destroyed any crust on earth that is that old. I beleive the oldest suviving earth rocks are in the 3.8 billion year range.
We know the age of the Moon by directly dating rocks from there. Since the Moon has no appreciable tectonic activity, and very little erosion, it’s crust has survived more or less intact. (if you call impacted by a billion meteors intact)
Actually, the currently favored theory about the origin of the Moon does involve just such a collision. Only it was with something much bigger than your typical asteroid, more like about the size of Mars.
However, this collision happened very very early in the history of the Earth. Long before any of those layers of sedimentary rock were laid down. Before Earth had a history, you might say. Definitely before life started. If something that big happened later, there would be evidence of the collision in the rocks.
I’m going to guess no, for a few reasons:
-first, such an impact would have to destroy the layers over the entire globe–not just the area surrounding the impact. I can’t see how this is possible without reducing the Earth to rubble.
-second, there would be a record, a layer of soot and ash over the entire planet. It would, I think, be very obvious.
-finally, I imagine such an impact would leave nothing on Earth alive. Anything that survived the initial impact (and no land organism would, unless very deep down) would die in the aftermath of global firestorms and nuclear winter.
Sweet! I wonder how long it would have taken for the Earth to cool down… ie: if there was a long term space habitat/mission that involved a large number of people, if they would be able to “colonize” the newly remade earth.
Probably not.
What would happen to the atmosphere if something like that were to occur? I imagine a sizeable chunk of it would be blown out into space.
I think a lot of people mistakenly think the Earth is solid rock. The crust is extremely thin. I once read that if you tried to draw a cross-section of the Earth to scale, it would have to be a circle about 8 feet across for the crust to be as thick as your pencil line. Below the crust, the mantle is not structured so that you’d see strata like the crust has.
Anyway, anything powerful enough to destroy strata worldwide would just melt the whold crust. Not just the top layers, but all the layers would be eliminated. Any impact that didn’t completely flip the crust over would be pretty easy to detect billions of years later.
I always wanted to write a story or book where there was an ancient civilization on Earth then an asteroid crashed into the planet. The ancient civilization planted some of their “DNA” into a simple lifeform before the impact. Then whoever could leave the planet left, the rest died (or something else…). The simple lifeform eventually evolved into…humans. Then blah blah we find the ancient civilization and blah blah.
I’m sure there is a book out there though with somewhat the same theme.
Ah! so, (and this is just a compete sci fi type question) in theory, there could ahve been a completely prosperous ecosystem here on earth, Perhaps even with creatures as intelligent as us here, that could have been wiped out (or left) by the massive impact that may have created the moon, and we, here today, would have no knowledge of it.
Probably there were no organisms on earth at the time of the impact, for the reason that it occured very very early in the formation of our solar system. That was the last big cataclysm to hit the Earth, but before that there might have been dozens as Earth condensed out of the solar disk. And Earth almost certainly didn’t have liquid water, or any free volatile on the surface at that time…probably the crust was liquid magma for most of this early history. It isn’t until the crust cooled down enough for liquid water and volatiles to be retained on the surface that life could begin. And even if the Earth HAD cooled enough for liquid water, and some life evolved just before the Moon creation impact, it is highly highly highly unlikely that that life was anything but very simple bacteria. Life arose very soon after the formation of the Earth, but for billions of years the most complicated organisms were bacteria. There is no reason to suspect that any earlier generation of life could have evolved into multicellular life thousands of times faster than the organisms we know about.
every 240 million years all earth surface is changed because of erosion subduction (continental drift) etc, so if a collition would happen it will just make that faster, so the song dust inb the wind is quite corrects “nothing lasts forever but the earth and sky”…
It is NOT true that every 240 million years the earth’s surface is changed. We have rocks that are 4 billion years old. It is true that very old rocks are very rare, since the rocks tend to be (as you said) eroded, subducted, melted, etc. But these processes aren’t uniform all over the earth. Some rocks are destroyed very quickly, most last for quite a while, and some are nearly as old as the Earth.
“The Inheritors” from the 1960s program Outer Limits, credited to Sam Newman, Seeleg Lester and Ed Adamson.
This program also had some interesting similarities to Star Trek’s “The Cage/The Menagerie,” as well as to a previous Outer Limits story “Second Chance,” which completely knots the loop because the alien costume in “Second Chance” was reused, IIRC, in “The Cage,” although it was cut from “The Menagerie.”
As luck would have it, I just finished taking an exam that covered this subject.
The idea of a meteorite wiping out early life is known as ** impact sterilization [\B]
Impacts from a 150 kilometer asteroids would vaporize the top layer of the ocean and would * probably * be enough to kill off all early life.
A certain impact sterilization would require a meteorite 350-400 kilometers across; big enough to vaporize the oceans and raise surface temperatures up to 2,000ºC.
The last sterilizing impact most like happened around four billion years ago.
While it is plausible that life evolved and was wiped out perhaps several times before the last impact sterilization it would not have been around long enough to develop into anything complex.
1.) This life would have probably been very simple, it took about a billion years for a complex cell structure of Eukaryotes to evolve.
2.) This life would have been non-dependent on oxygen, because oxygen in our atmosphere arose from because of at least a billion years of build up from blue-green algae (cyanobacteria)
3.) This life could probably could not have lived on the surface of the Earth because an Ozone layer did not yet exist, and the Earth would have been constantly bombarded by deadly UV radiation.
Hope this is of some use to you. If anyone is interested, all the information in this post was taken from chapters 4-5 of Life in the Universe by Bennett, Shostak, and Jakosky, copyright 2003 by Pearson Education, Inc.
Seems to me a lot of the "it couldn’t have"s in this thread are basically arguing in a circle.
Given that this planet, even now, seems to be rather unique in terms of its life-generating and life-sustaining properties–how can one generalize about what might have been the case here during the first billion years or so?
That is: Precisely how can we be certain that primeval Terra didn’t have an ozone layer? Or a cool surface? Or a thriving ecosphere, maybe even with people of a sort? What gives anyone license to declare how long it takes for “sophisticated” life forms to evolve?
Surely the “moon event” would have wiped out and scrambled every trace of anything on top of, or even within, the crust. If the thin thin THIN layer of organic material at the surface were diluted throughout a vaporized crust (and some of the outer mantle, no doubt…)–it seems it would take some mighty sophisticated analysis to detect same.
And paltry Project Moho was cancelled.
Now, if someone were to find a gold chain embedded in multi-billion-year old rock…
Since the moon keeps getting mentioned, I should point out that if some future aliens wandered by to find Earth a big splattered mess, they might also find the various Apollo landers on the lunar surface which would serve as evidence of our existence.
For that matter, they could play the gold record stuck on the side of the Voyager probes. Humanity has already left physical evidence of itself beyond the Earth, which would survive even a huge catastrophe.
Thanks Mjollnir , I’ll have to check that out. There are stories like that somewhere (I remember hearing about some) it’s just I don’t remember what they were.
