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Tunguska mystery explained ?

 
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Kalinoux
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MessagePosté le: 29/06/2007 16:59:33    Sujet du message: Tunguska mystery explained ? Répondre en citant

Hello,

It seems that some researchers think to have solved the Tunguska mystery :

Arrow Tunguska

Citation:
Crater Could Solve 1908 Tunguska Meteor Mystery

By Dave Mosher
Staff Writer
posted: 26 June 2007
06:27 am ET


In late June of 1908, a fireball exploded above the remote Russian forests of Tunguska, Siberia, flattening more than 800 square miles of trees. Researchers think a meteor was responsible for the devastation, but neither its fragments nor any impact craters have been discovered.

Astronomers have been left to guess whether the object was an asteroid or a comet, and figuring out what it was would allow better modeling of potential future calamities.

Italian researchers now think they've found a smoking gun: The 164-foot-deep Lake Cheko, located just 5 miles northwest of the epicenter of destruction.

"When we looked at the bottom of the lake, we measured seismic waves reflecting off of something," said Giuseppe Longo, a physicist at the University of Bologna in Italy and co-author of the study. "Nobody has found this before. We can only explain that and the shape of the lake as a low-velocity impact crater."

Should the team turn up conclusive evidence of an asteroid or comet on a later expedition, when they obtain a deeper core sample beneath the lake, remaining mysteries surrounding the Tunguska event may be solved.

The findings are detailed in this month's online version of the journal Terra Nova.

Submerged evidence

During a 1999 expedition, Longo's team didn't plan to investigate Lake Cheko as an impact crater, but rather to look for meteoroid dust in its submerged sediments. While sonar-scanning the lake's topography, they were struck by its cone-like features.

"Expeditions in the 1960s concluded the lake was not an impact crater, but their technologies were limited," Longo said. With the advent of better sonar and computer technologies, he explained, the lake took shape.

Going a step further, Longo's team dove to the bottom and took 6-foot core samples, revealing fresh mud-like sediment on top of "chaotic deposits" beneath. Still, Longo explained the samples are inconclusive of a meteorite impact.

"To really find out if this is an impact crater," Long said, "we need a core sample 10 meters (33 feet) into the bottom" in order to investigate a spot where the team detected a "reflecting" anomaly with their seismic instruments. They think this could be where the ground was compacted by an impact or where part of the meteorite itself lies: The object, if found, could be more than 30 feet in diameter and weigh almost 1,700 tons-the weight of about 42 fully-loaded semi-trailers.

Caution for now

From a UFO crash to a wandering black hole, wild (and wildly unsupported) explanations for the Tunguska event have been proposed. Alan Harris, a planetary scientist at the Space Science Institute in Boulder, Colorado, said the proposal by Longo's team isn't one of them.

"I was impressed by their work and I don't think it's something you can wave off," said Harris, who was not involved in the research.

Longo and his team "are among the recognized authorities on Tunguska" in the world, Harris told SPACE.com. "It would be thrilling to dig up chunks of the meteor body, if they can manage to. It would lay the question to rest whether or not Tunguska was a comet or asteroid."

Some researchers, however, are less confident in the team's conclusions.

"We know from the entry physics that the largest and most energetic objects penetrate deepest," said David Morrison, an astronomer with NASA's Ames Research Center. That only a fragment of the main explosion reached the ground and made a relatively small crater, without creating a larger main crater, seems contradictory to Morrison.

Harris agreed that physics could work against Longo's explanation, but did note that similar events-with impact craters-have been documented all over the world.

"In 1947, the Russian Sikhote-Alin meteorite created 100 small craters. Some were 20 meters (66 feet) across," Harris said. A site in Poland also exists, he explained, where a large meteor exploded and created a series of small lakes. "If the fragment was traveling slowly enough, there's actually a good chance (Longo's team) will unearth some meteorite material," Harris said.

Longo's team plans to return to Lake Cheko next summer, close to the 100th anniversary of the Tunguska Event. "This is important work because we can make better conclusions about how cosmic bodies impact the Earth, and what they're made of," Longo said. "And it could help us find ways to protect our planet from future impacts of this kind."


Now the question : where can I get Terra Nova magazine Neutral

... and wait for confirmation about this explanation Wink So much explanations have been proposed for Tunguska events, that I hope we'll have more details in a near future Smile

Have a nice week end,

Respect

Kalinoux
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MessagePosté le: 29/06/2007 16:59:33    Sujet du message: Publicité

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André L.
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MessagePosté le: 17/09/2010 22:14:25    Sujet du message: Tunguska mystery explained ? Répondre en citant

 
 
Le 30 juin 1908, une gigantesque explosion se produisit au dessus de la Tunguska en Sibérie, ravageant 2000 km2 de taïga. Rien ni personne ne permet aujourd’hui encore de pouvoir expliquer ce phénomène.  
 
Dans le village de Nizhne-Karelinsk, distant de 360 km de Tunguska, les paysans ont observé un objet très brillant et blanc-bleuté, trop brillant pour être observé à l'oeil nu, voler assez haut au-dessus de l'horizon nord-ouest. Le ciel était clair excepté un petit nuage sombre près de l'horizon vers lequel se dirigeait l'objet.  L'atmosphère était chaude et sèche. L'objet tomba verticalement durant dix minutes. Il avait une forme cylindrique. Quand il approcha du sol on aurait dit qu'il fut pulvérisé et à sa place se forma un immense nuage de fumée noire.  
 
Les arbres tels que vu par Kulik en 1928 
 
 
Une explosion comme jamais on en avait entendu de mémoire d'homme retentit. Son écho fut perçu jusqu'à 1000 km de distance ! Au même instant, à exactement 0h14m28s TU un séisme très important par sa durée et de magnitude 5 fut enregistré jusqu'au Etats-Unis, dont l'épicentre se situait en plein coeur de la Sibérie orientale. 
 
Les paysans de Nizhne-Karelinsk entendirent un bruit sourd, pas un bruit comme le tonnerre, mais comme si de grosses pierres dévalaient ou comme un coup de feu. Toutes les habitations furent secouées et au même moment, une langue fourchue de flammes perça les nuages. La vielle femme pleura, tous imaginaient que la fin du monde approchait. 
 
Sur les lieux, une bonne partie de la forêt d'Irkoutsk sur 45 km2 avait été bouleversée et en l'espace de 2 semaines 2000 km2 de bois disparurent en fumée ! 60 millions d'arbres furent couchés radialement sur le sol, brûlés comme des allumettes, autour d'une zone centrale où tout fut pratiquement incinéré. A quelques kilomètres de là, les arbres étaient décapités ou carrément éclatés comme de vulgaires pailles ! 
 
A titre de comparaison la tempête de Noël 1999 qui déferla sur l'Europe détruisit 15 millions d'arbres en France et elle s'étendit sur pratiquement 3 jours. L'explosion du Mont St.Helens en 1980 (env. 400 MT, VEI5) détruisit plusieurs millions d'arbres également. Mais ici s'arrête la comparaison. 
 
Les membres de l'expédition organisée par la fondation publique d'état de la Sibérie "Phénomène Spatial de Tunguska", au cours du mois de juillet 2004, affirment avoir découvert les débris d'un appareil extraterrestre qui pourrait être à l'origine de l'explosion phénoménale du 30 juin 1908. 
 
Une roche de 50 kilos a été envoyée à Krasnoyarsk pour analyse. 
 
Pour mémoire, le 30 juin 1908, les habitants de la Sibérie ont observé une gigantesque boule de feu presqu'aussi brillante que le soleil traversant le ciel. Plusieurs minutes plus tard, une explosion aérienne illumina le ciel, l'onde choc brisa les vitres jusqu'à 600 km à la ronde, plus de 60 millions d'arbres furent couchés sur plus de 2000 km2. L'onde choc sismique fut ressentie sur tout le continent eurasien et les variations de pressions atmosphérique furent même enregistrée en Grande-Bretagne. 
 
Partie 1 : a partir de 07:35 du début de se vidéo, ils racontent cette extraordonaire événement qui a eu lien le 30 juin 1908 au dessus de la Tunguska en Sibérie. 
 
 
 
Partie 2 : a partir du début de se vidéo jusqu'à 09:25, ils racontent la suite de cette extraordinaire événement qui a eu lieu le 30 juin 1908 au dessus de la Tunguska en Sibérie. 
 
Différentes hypothèses ont été émises pour expliquer cet évènement, de la météorite, à la comète jusqu'au vaisseau extraterrestre... 
 

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Dernière édition par André L. le 08/11/2010 17:13:20; édité 1 fois
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MessagePosté le: 07/11/2010 22:46:30    Sujet du message: Tunguska mystery explained ? Répondre en citant

Another explanation ?

Citation:
Mystery of Tunguska meteorite solved (25.10.2010)


102 years after the fall of the famous celestial body in Tunguska taiga, scientists finally managed to identify the crash site of one of its fragments and examine the unusual composition of the substance of this space creature. The study was conducted using a unique instrument - GPR. As a result, it was proved that it was not a meteorite, but a comet.

The mystery of the Tunguska meteorite has long attracted the attention of researchers from around the world. Perhaps no visitor from outer space in the history of the mankind created so much noise, both literally and figuratively. The most surprising is the fact that in some hundred-odd years that have passed since that event, scientists have failed to solve this puzzle.

What happened in the Podkamennaya Tunguska River back in 1908? The witnesses say that on June 30 at about 7am something resembling a giant ball flew over the territory of Central Siberia in the north-western direction.

Its flight was accompanied by sound and light effects, and ended with a powerful explosion followed by a felling of forest between the rivers Kimchu and Hushmo - tributaries of the Podkamennaya Tunguska.

The explosion occurred at 7:14am local time. It was accompanied by a powerful earthquake which was registered by most seismological stations of the world, and air waves. It was noted that the echo of the explosion at Tunguska was heard over 800 kilometers away from the epicenter, the blast felled 2100 km ² of forest, and within a radius of 200 km windows of some houses were broken. Soon after, a magnetic storm began which lasted 5 hours.

"I was swinging my axe when the sky in the north has divided into two parts and a fire appeared in it above the forest, which covered the entire northern part of the sky. At that moment I felt so hot, as if my shirt was on fire. I wanted to tear and throw off my shirt, but the sky slammed shut and there was a strong blow. I was dropped off the porch and blown away.

After the strike came a tapping, as if rocks were falling from the sky or guns fired, the ground trembled, and when I lay on the ground, I feared that the rocks would break my head. At a time when the sky opened up, a hot wind swept from the north, like from a cannon, which has left traces on the ground in the form of tracks. Then it turned out that many of the windows shattered, and the iron tab for door lock in the barn was broken."
Somewhat later in the night on June 30, an intense glow of the sky, night shining clouds, and unusually colorful dusk were observed in dozens of settlements in Western Europe and Russia. By spectral observations made in Germany and England, this glow was not a part of the aurora, and was of some different nature.

In studying this phenomenon, French astronomers first suggested that on June 30 Earth clashed with a cloud of cosmic dust. Later this hypothesis was supported by several other prominent scientists, in particular B. I. Vernadsky. However, he thought that perhaps it was not a simple cloud of dust but a frozen cloud, that is, a fragment of the comet's nucleus. However, most astronomers thought that the Tunguska event was the result of falling of a giant meteorite on Earth.

The first expedition to the site of the disaster was sent only in 1921, but its members failed to get there. Only in 1927 a research team led by Leonid A. Kulik was able to reach the epicenter of the explosion.

The most interesting thing is that they have not found a crater left by a meteorite impact on Earth. Another oddity of the Tunguska event was that the forest was knocked over a large area close to the presumed site of a meteorite, but at the very epicenter of the explosion it remained standing. It seemed that the "alien" exploded in the air and did not reach the planet's surface.

Over the subsequent years, researchers have not managed to find a meteorite crater or fragments of the celestial body itself. Many scholars have asked a logical question whether it was a meteorite.

There were hypotheses that the explosion was not made by a celestial body, but by Earth's marsh gas that escaped from within (though the traces of its presence in this place were also not found), or that the cause of the accident was secret experiments of Nikola Tesla with electricity. However, all these theories also have not been confirmed.

The first steps toward unraveling the mystery of Tunguska were made in 2007 by a group of Italian researchers. Their expedition conducted geological surveys of the bottom and banks of Lake Cheko, located a few miles from the center of the explosion, and determined that this pool was a conical hopper with a fairly great depth of 50 meters.

All this suggests that a piece of the Tunguska meteorite fell there. Other candidates for the role of "craters" were nearby swamps Bublik, Suslov and Cranberry funnels.

In 2010, an expedition of Vladimir Alexeev with Troitsk Innovation and Nuclear Research Institute (TRINITY) set off to the area of the fall of the meteorite. Scientists brought ground penetrating radar - a unique instrument capable of lighting the ground to the depth of 100 meters. As a result, the examination of Suslov crater found that the crater resulted from a severe impact of a celestial body on the surface of the Earth.

The bottom of this funnel was structured as follows: the top layers were modern permafrost, below were damaged layers, and finally, deeper, the fragments of the cosmic body were discovered. Preliminary analysis showed that it was a huge piece of ice that apparently broke away from the comet's nucleus.

The famous "tailed stars" consist of very unusual ice formed with water frozen by space, methane and other gases with a mixture of solid particles. The kernel that weighs hundreds of billions of tons is followed by multi-kilometers tail, consisting of rarefied gases formed by evaporation of the ice by the sun.

It turns out that when approaching Earth, icy nucleus of comet shattered into fragments, which were scattered by the explosion several kilometers away. Having fallen on the surface of our planet, they formed several craters, which include Suslov funnel examined by the group of Alekseev. The tail of a comet that broke off scattered through the atmosphere, causing a very strange glow of the sky, which was observed on the night after falling of the celestial body.

Also, scientists were able to study traces of the matter of non-terrestrial origin detained in the resin of trees in the epicenter of the explosion (they still grow there). The researchers concluded that the substance was very similar to cosmic dust which is a part of the comet nucleus. This once again convinced them that the Tunguska "stranger" should be called not a meteorite, but a comet.

Thus, the theory suggested many years ago by Academician V. I. Vernadsky about a comet nature of the Tunguska meteorite has now received actual confirmation. It is interesting that it took scientists nearly a hundred years to solve this mystery. But as they say, better late than never.



Tunguska explained by a comet?


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MessagePosté le: 18/12/2017 10:42:26    Sujet du message: Tunguska mystery explained ?

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