Russian
scientist Leonid Kulik photographed these trees knocked over like matchsticks
near the epicenter of a mysterious Siberian blast in 1927.
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It
was the largest impact event on or
near Earth in recorded history. An
explosion three to six miles above the surface of the earth is estimated to have been in the range of 10–15 megatons of TNT—about 1,000 times
greater than that of the atomic bomb
dropped on Hiroshima. It knocked down virtually everything
standing in 830 square miles, shook
the earth the equivalent of a 5.0 earthquake
on the Richter scale, caused fluctuation
in atmospheric pressure measured in London, and caused a stratospheric cloud of ice crystals to orbit the earth for months affecting the climate of the Northern Hemisphere.
But
because the explosion on June 30, 1908 occurred over one of the most remote and
underpopulated regions of the earth—an almost unexplored (by Europeans) forest by the near the Podkamennaya Tunguska River deep in
south-central Siberia it was barely
noted at the time. Subsequent events—World War I, the Russian Revolution, and the Civil
War that followed meant that the site of the Tunguska Event was not investigated until an expedition was finally
mounted in 1927, 19 years after the explosion.
On
July 2 first reports were printed in a Siberian
newspaper.
On the 17th of
June (old calendar still in use in Russia), around 9 a.m. in the morning, we
observed an unusual natural occurrence. In the north Karelinski village [200 verst north of Kirensk] the peasants saw to the north west, rather high above the
horizon, some strangely bright (impossible to look at) bluish-white heavenly
body, which for 10 minutes moved downwards. The body appeared as a “pipe”,
i.e., a cylinder. The sky was cloudless, only a small dark cloud was observed
in the general direction of the bright body. It was hot and dry. As the body
neared the ground (forest), the bright body seemed to smudge, and then turned
into a giant billow of black smoke, and a loud knocking (not thunder) was
heard, as if large stones were falling, or artillery was fired. All buildings
shook. At the same time the cloud began emitting flames of uncertain shapes.
All villagers were stricken with panic and took to the streets, women cried,
thinking it was the end of the world.
The author of
these lines was meantime in the forest about 6 verst [6.4 km] north of Kirensk,
and heard to the north east some kind of artillery barrage, that repeated in
intervals of 15 minutes at least 10 times. In Kirensk in a few buildings in the
walls facing north east window glass shook.
Scattered
report reached Moscow within days, but received surprisingly scant
interest. No official or scientific
investigations were undertaken to find out what the hell happened out there in
the boonies.
Finally
in 1921, as the Civil War was winding down, mineralogist Leonid Kulik was dispatched by the Soviet Academy of Sciences to the Podkamennaya
Tunguska River basin not to investigate the incident 13 years early but as part
of a survey to discover possible natural resources in the remote area. He began hearing stories of the mysterious
event from locals, and started informally collecting evidence as well as he
could without actually traveling to the area of the impact. He concluded a large meteor or small asteroid had
either struck the earth or exploded on entry relatively close to the surface.
Kulik
spent years trying to convince Soviet science authorities to fund a full scale
expedition to the site. But the
practical commissars keeping a close
eye on those foolish scientists had little interest in abstract science or
basic research. They insisted that some tangible
and practical economic benefit must be the result of any investigation. Finally he convinced them that he might be
able to locate a very large nickel/cadmium/iron
meteorite, the kind representing some of the densest and hardest stone
found on earth, which could be useful in the Soviet steel industry. He had to do
this with both fingers crossed behind his back knowing that even if such a
meteorite had struck the earth, it would have shattered into small fragments
spread over a wide area and unlikely to be recoverable in any economically viable
amounts.
None-the-less
Kulik arrived in the area in 1927 at the head of a well-supplied expedition. He contacted with local Evenks, indigenous semi-nomadic reindeer herders and hunter to guide him
form remote Russian trading outposts to the site. Travel through dense forests cut by numerous
rivers and streams was extremely difficult.
But after weeks of travel the group neared the target area. Then, just south of the site, the Kulik guides flatly refused to take him
further, fearing possible supernatural
beings called valleymen
associated with the site. Kulik had to
turn back to a village and arrange for new guides.
Finally
the expedition reached a ridge overlooking the impact area. To Kulik’s surprise, he could detect no discernible impact crater. Instead around ground zero a vast zone more than
5 miles across of trees scorched and devoid of branches, but standing
upright. Trees further from the center
were more lightly singed, but all knocked over in a direction away from the
center—a giant ring of flattened trees radiating from an invisible center.
Kulik
led three more expeditions to the area looking for evidence of an impact. His best hope seemed to be numerous small pothole bogs which he thought might
have been created by meteorite fragments.
But this turned out to be a blind alley. Draining one turned up an old tree stump at
its bottom, not extraterrestrial stone.
The
Soviets continued to send teams of investigators to the region for decades but
the mystery of just what had happened only deepened. Eventually microscopic beads of silicate and magnetite were found in the soil, and still later similar beads
were found in the resin of some
trees. The beads or spheres, also
contained significant traces of nickel iron similar in composition to that
found in meteorites. All of this
bolstered the opinion that an object from space was involved, but that it had
likely been virtually destroyed by an explosion in the atmosphere. That became the most widely accepted
theoretic explanation of the event.
Atmospheric
nuclear tests it the ‘50’s and ‘60’s
seemed to confirm the hypothesis that an asteroid exploded. Air bursts over forests showed that trees
directly under the blast were stripped as the blast wave moved vertically downward, while trees
farther away were knocked over because the blast wave was traveling closer to horizontal when it reaches them.
By
then aerial surveys showed the blast
area was actually in the “shape of a butterfly
with wings outstretched” occupying an area of 830 square miles, with a wingspan
of 43 miles and a body length of 34 miles.
Soviet experiments performed in the mid-‘60s, with model forests and
small explosive charges slid downward on wires, produced strikingly similar butterfly-shaped
blast patterns suggested that an extraterrestrial
object had approached at an angle of
roughly 30 degrees from the ground
and 115 degrees from north and had exploded in mid-air.
Making
up for the lack of interest in the first few years, the Tunguska Event
continues to interest and challenge science with new techniques and
technologies applied almost yearly to discovering just what happened. The exploding asteroid theory remains the top
contender, but the continuing absence of any fragment of the object has opened
the door to other conjectures.
Among
the several theories advanced, the one which picked up the most steam was that
instead of an asteroid, the object was a small comet or a fragment of a
larger comet that had disintegrated in orbit earlier. Advanced by some Soviet scientists in the
1930’s, the fact that the head of a comet—made up of ice particles and space dust exploding in the atmosphere would
explain why no physical debris has been found on earth. Dissipation of the ice crystals into the upper
atmosphere could also explain the “glow” that was reported for some days after
the event and the orbiting particles that reduced sunlight hitting the earth
over the next year.
In
the ‘70’s there Soviets even advanced a candidate, fragment of the short-period Comet Encke, which is
responsible for the Beta Taurid meteor
shower which coincided with the event.
Later Western research has cast doubt on the comet theory pointing out
that a comet reaching the atmosphere at the low angle expected would have
exploded or vaporized far earlier and not nearly reached the surface, if a
handful of miles can be said to be near the surface. Other research showed that the object came in
a direction from the asteroid belt.
If
the comet idea was doubtful, scientist were still troubled by the absence of
physical evidence that a hard stony object like an asteroid should have left
behind. Then in 2007 a candidate for the
long sought impact crater was brought forwards—Lake Cheko, a small, bowl-shaped lake approximately a little more
than 4 miles north-northwest of the epicenter.
Magnetic readings indicated a
possible meter-sized chunk of rock below the lake’s deepest point that may be a
fragment of the colliding body and chemical analysis of the lake silt has supported
a creation about the time of the impact.
Scientists from scientists from the University
of Bologna led by professor Giuseppe
Longo have pressed the case that the long missing impact crater and a fragment
may have been found. Other experts are
skeptical.
In
2005 a near earth object identified
as 2005 NB56 was observed for a 17 day period as it neared the
earth. Its exact orbit could not be
calculated, but some scientists believe that a large fragment of it in may have
brushed the atmosphere in 1908 causing the explosion and then skipping or
bouncing back into orbit around the sun.
They believe that the object will again near the earth in 2048 and hope
that better calculation of its orbit would be able to confirm it as a
candidate.
A
couple of proposals have been put forward involving a “natural H-bomb.” In these scenarios unusually large
concentrations of deuterium—heavy
hydrogen—in the head of a small comet underwent a nuclear fusion reaction when
it entered the atmosphere. Two or three
explanations of how this could have been triggered have been advanced. Most scientists believe that that the
concentration of radioactive isotopes
in the blast region to be inconsistent with those expected following a nuclear
explosion.
Probably
the oddest of all theories seriously advanced was that the earth was actually
struck by a small black hole which
passed through the planet exiting on the other side. This one has most scientists shaking their
heads in disbelief. If this were the
case there should have been and exit explosion of similar magnitude. Even though at the expected trajectory, the
exit would have occurred somewhere North
Atlantic, closer than the impact event to the seismic recording stations that collected much of the evidence of
the event and would likely have been observed by ships in the region.
A
similar proposal suggested a collision with an anti-mater object. Neither
of those explanations takes into account the orbiting dust trails in the
atmosphere or the distribution of high-nickel magnetic micro-beads around the
impact area.
One
scientist has even suggested that there was no collision or impact of any sort,
but rather huge eruption and explosion of 10 million tons of natural gas from within Earth’s crust. Few are taking a bite out of that apple,
especially since just as an impact crater has been hard to find, there is no
geologic evidence of an outward explosion from the crust.
Despite
all of the conjecture most scientists keep coming back to that wayward
asteroid.
But
I am sure as I type that the History
Chanel is preparing a “documentary” on the Tunguska Event on aliens.
Or maybe they already have….