Tunguska: T + 100 years

http://www.space.com/news/080630-mm-tunguska-mystery.html

As usual, the important news is always several days behind, and this article from Space.com reminded me of an important anniversary of disaster, and almost supernatural mystery. No, its not the 100th anniversary of the Cubs last World Series (though, it is that too .. coincidence????)

Rather, it is the 100th anniversary of the Tunguska event. As the warden in Alien 3 would say: here are the facts

Tunguska is a river that flows through eastern Russia (Siberia), forming a namesake river valley. That part of Siberia is rather swampy and forested, vs. bring the perpetual tundra that many think it might be. It is remote and sparsely inhabited.

On the morning of June 30, 1908 (actually, to even show the press doesn’t have it right, the actual anniversary was June 17, because Russia was not using the Julian calendar), something amazing happened. An explosion (we assume) occurred where there was no factory, military base, etc, etc. How big? about 12 megatons (or 1,000 times more power than the nuclear device dropped at Hiroshima). Over 800 square miles of trees were knocked down from a central point.

Because the area was remote, and the government of the Tsar had more pressing business (even though the Revolution was about ten years away, the seeds for revolution were already foaming), no one went out to follow up until about 1921!

Thoughts of a primitive nuclear device can be ruled out: there is no residual radiation. Certainly, if every stick of dynamite in the Czar’s army had been set off, it might have gotten close, but there was no such stash of conventional explosive. It certainly was not a man made event.

That aside, what causes a nuclear-sized explosion without the nuclear? That has been the mystery for the better part of the century.

The most ludicrous idea is that of a crashed UFO, despite there being zero wreckage, no little grey cadavers, and no other evidence (though as is the case with conspiracy theorists, it is the very lack of evidence that means their idea either must be true, or at least must be accepted. Fortunately most people can think with clearer heads than that).

Even back in 1921, the prevailing theory was an extraterrestrial crash, but not by ET and his friends. Rather, the idea was that an asteroid or comet may have been responsible. Debris was found at the epicenter of the event, and a great deal of evidence based on the ratio of chemical isotopes points to an asteroid, though curiously to the people of the time: there was no real crater. People were aware that things did occasionally fall from the sky, but when they fell, there was a crater. This would be a big object ….. hence, big crater! But no crater was puzzling?!

As time has progressed, it is now thought that this was likely an explosive breakup in the atmosphere; thus only little pieces of asteroid actually hit the Earth, but the powerful explosion still knocks down the trees.

Why is this event so much more than a curiosity? There are more facts: our solar system; at least the inner part of it, is something akin to a shooting gallery. Asteroids and comets are constantly traversing Earth’s orbit. Everyday, little specks of dust rain down on the Earth (odd to think that the dust that you find on your table is a combination of dead skin and the remains of those little asteroids falling to Earth ….. as I’ve told my students, if you want to touch something that has been in space, volunteer to dust your house on cleaning day. A large percentage of that dust is ex-asteroid and ex-comet. But I digress.

Gene Shoemaker, a geologist whom I have studied a bit, was the first person to put serious scientific arguments forward about extraterrestrial impacts not only being real phenomena, but being real phenomena that can have some very tragic consequences. Gene is no nut: Gene was the world’s leading crater authority. When it came time to go to the moon, he trained the astronauts in geology. He would have been the first (and to date only) scientist on the moon had his health not gotten in the way (one of his students, Harrison Schmitt got the go instead).

Shoemaker and his wife and a colleague, David Levy, were also the discoverers of the first comet that we have actually witnessed colliding with a planet (talk about trillions to one! after years of claiming that asteroids could hit a planet, he actually helps find the first one that we see doing it), when Shoemaker-Levy-9 broke apart by the tidal forces of Jupiter’s gravity, and then plunged into its atmosphere piece by piece. Some of the observed explosions were nearly as large as the Earth itself! But I really digress.

Or maybe I don’t. That’s the point We talk about the fear of ruining the world with pollution and such. Of course, as many scientists point out: we aren’t destroying the Earth, because it is far to complex and massive a system to be destroyed; rather we are destroying its ability to sustain our species. But at the same time, we are on the clock. One day (and it will happen; it is only a a matter of when) a large hunk of rock is going to be on its way, in orbit around the sun, when the Earth will stray to close, and the result will be a potentially very quick end. The good news is that we do have tools at are disposal to stop this.

What are we doing about it? Keep in mind: The estimates of what hit Tunguska a hundred years ago was that it was small ….. I’d hate to think about a big one hitting us.

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