The Bolide of Tunguska

Early in the morning of June 30, 1908 residents of Tunguska in Siberia woke up to an explosion in the sky  above them. It is believed to have been caused by the breakup of a large meteorite in the atmosphere.  The bolide was said to be as bright as the Sun.  There were few witnesses, and it was fortunate that Russian scientists did collect accounts from them.

The explosion stripped or felled trees in a butterfly pattern over 80 km wide.  Animals were burned to death.  Inhabitants were flown through the air, one even landed in a tree and later died. Some died from practically vomiting their stomachs out .

Black rain fell over the area. For many weeks the night skies over Europe and Russia glowed orange and bright enough for people to read the newspapers in the dead of night.  Boats on the opposite side of the globe had their electronics burned out.  Dust and smoke filled the atmosphere worldwide for several months.  The size of the blast has been estimated to have been around 15 megatons. 

In Tunguska, Siberia it was a clear day and hot on the last day of June in 1908 when a brilliant orb as bright as the sun appeared in the morning sky.  It was seen for about ten minutes.  Then all of a sudden there came a flash of light followed by an enormous explosion with the energy of over a thousand atom bombs and with a force to flatten more than 800 square miles of trees. Trees, humans and animals were picked up and thrown through the air by a shockwave in a pattern resembling a gravity current. Windows were blown out and huts flattened.

Investigators originally thought that a meteorite caused the destruction, but no evidence emerged to prove their hypothesis. It is believed by most scientists that a core of a comet or an asteroid had exploded above the ground. So other theories have been proposed. Some propose that perhaps an extraterrestrial spaceship crashed. Other’s think it was a geophysical event. Some think that it was one of Tesla’s experiments.  (Dr. Nikola Tesla the scientist and inventor who worked extensively with electricity and was known to be experimenting in 1908).  So far the Tunguska explosion is still a mystery.

Some curiosities remain. 

Spheres of magnatite were found in abundance is especially near the epicenter.

Nanodiamonds were also found in the area. 

Biological mutations were also discovered.

Of interest is the appearance of those noctilucent clouds as was first seen after Krakatau.

Recently, Giuseppe Longo, a physicist at the University of Bologna, Italy, discovered a crater like lake which he believes will solve this mystery. 

While investigating Lake Cheko, he and his team discovered that it was 164 foot deep cone shaped lake only 5 miles from the epicenter of the Tunguska event.  They hypothesize that it was a low-velocity impact crater.  In other words the exploding bolide caused a piece to  impact the ground and formed this lake. 

They took a six foot core sample which revealed a fresh mud-like sediment on top of "chaotic deposits." However to prove their theory the would need least a 33 foot core sample to find the possible meteor in the impact crater.  They plan to return for the evidence in the near future.  Usually when a meteor does in fact hit the ground it creates a crater with a flap, a mound of ejecta, around the rim.  An absence of a flap around Lake Cheko detracts from Longo’s theory.  However, Longo believes that piled up ejecta just slid into the lake.

Note that the appearance of the chaotic deposits could have been caused by a reverse shock of a gamma ray burst.

The following accounts are paraphrased, but based on information provided by witnesses and a newspaper concerning the catastrophy at Tunguska.

Semenov meandered quietly out of the house with his breakfast.  He breathed deeply as he took in the fresh morning air.  Summer in Siberia brought a bustle to the Vanavara trading post near his house.  Even though he had much work to do, he welcome the chance to mingle.  As he sat down to eat, something caught his attention, a light due north. It was bright and blinding.  After minutes past, a flash of light split the sky in two. Then a fire appeared low and wide over the forest.  The fire grew to cover as far as Semenov could see to the North. The heat of the fire radiated through Semenov’s layers of garments so that it seamed to him that his clothes were on fire.  Semenov had to rip off his shirt and throw it down.  Just then a force pick him up off the ground.  As he was flying through the air, he heard a thump.  Then as he hit the wet sod beneath him, everything went black.  The next thing he remembered his wife was dragging him back into the house.  Just as he was feeling a little comfort for being inside, there came the noise, so loud that he had to cover his ears.  It seemed to him that a hefty cannon was fired or heavy rocks were falling.  He ducked as if to avoid being hit by whatever made all that ruckus.  Heavy hot winds rushed between houses leaving barren trails and destroying crops.  Later he found out that windows shattered and an iron lock on his barn had snapped in two.

Semenov told his story to Leonid Kulik in 1930. 

Young Chuchan woke up with an uneasy feeling in his gut.  He looked over at his brother, Chekaren, who also was sleeping in hut.  Chekaren opened his eyes and they looked at each other for a moment when something shoved them.  Chekaren asked his brother if he could hear the birds flying overhead. Chuchan could hear a whistling noise and felt a strong wind.  They had no idea what was happening outside the hut.  Chuchan got shoved again, this time so hard he landed in the fire.  The boys began to call to their father, mother and brother, but no one answered.  They heard trees falling and a loud thunder.  The ground rocked the hut at the same time a wind blew the hut down over on top of the boys.  Looking up through the broken hut, Chuchan could see that the trees were on fire and the sky was bright for his eyes. It was as if there were many suns shining.  There came one thunderclap after another, but there were no clouds anywhere to be seen.  The boys worked to free themselves of the debris of the fallen hut.  Then from a different location, they saw another flash, and heard another loud thunder.  Then the wind came again and knocked both of them off their feet. Trees fell and the tops of some trees snapped off.  Chekaren pointed to another flash of light, and the boys heard another thunder which was not as loud this time.  Later, there was one more small thunder.

Chuchan told his story to I.M. Suslov in 1926. 

References: 

http://science.nasa.gov/headlines/y2008/30jun_tunguska.htm

http://thunderbolts.info/tpod/2007/arch07/070404tunguska2.htm