tunguska

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June 30th 1908: Tunguska event

On this day in 1908 just after 7.00am a very powerful explosion occurred in the skies above Siberia, in modern day Russia. The explosion was caused by the breakup and impact of a large meteorite. It was the largest impact event in Earth’s recorded history. The explosion was 1,000 times more powerful than the atomic bomb dropped on Hiroshima. Around 80 million trees were knocked down by the shock wave from the impact. The cause of the event  puzzled scientists for many years, but it has recently been established that a meteorite was the cause.

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What happened in Tunguska in 1908?

On June 30, 1908, in a remote part of Russia, a fireball was seen streaking across the daytime sky. Within moments, something exploded in the atmosphere above Siberia’s Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia.

This event – now widely known as the Tunguska event – is believed to have been caused by an incoming meteor or comet, which never actually struck Earth but instead exploded in the atmosphere, causing what is known as an air burst, three to six miles (5–10 kilometers) above Earth’s surface.

The explosion released enough energy to kill reindeer and flatten trees for many kilometers around the blast site. But no crater was ever found.

At the time, it was difficult to reach this remote part of Siberia. It wasn’t until 1927 that Leonid Kulik led the first Soviet research expedition to investigate the Tunguska event. He made a initial trip to the region, interviewed local witnesses and explored the region where the trees had been felled. He became convinced that they were all turned with their roots to the center. He did not find any meteorite fragments, and he did not find a meteorite crater.

Over the years, scientists and others concocted fabulous explanations for the Tunguska explosion. Some were pretty wild – such as the encounter of Earth with an alien spacecraft, or a mini-black-hole, or a particle of antimatter.

The truth is much more ordinary. In all likelihood, a small icy comet or stony asteroid collided with Earth’s atmosphere on June 30, 1908. If it were an asteroid, it might have been about a third as big as a football field – moving at about 15 kilometers (10 miles) per second.

Because the explosion took place so long ago, we might never know for certain whether it was an asteroid or comet. But in recent decades astronomers have come to take the possibility of comet and asteroid impacts more seriously. They now have regular observing programs to watch for Near-Earth Objects, as they’re called. They also meet regularly to discuss what might happen if we did find an object on a collision course with Earth.

Source & Credit: EarthSky

Remembering the Tunguska event: Today’s meteorite strike in Russia recalls the famous ‘“Tunguska event,” of 1908, in which a powerful explosion rocked the Podkamennaya Tunguska River in Russia. The cause of the explosion, estimated to be between 5 to 30 megatons ofTNT, has been speculated to be a meteor exploding in the atmosphere and crashing into the Earth.

For a frame of reference, the atomic bomb dropped on Hiroshima possessed the strength of just 16 kilotons.

Though nowhere near as damaging as the Tunguska explosion, which lit up skies from Europe to Asia for days afterward, today’s disastrous meteorite strike casts a tragic pall over the excitement over the asteroid D14, which is projected to narrowly miss Earth.

Photo: Trees strewn across the Siberian countryside in 1953 — 45 years after the Tunguska event. Credit: Associated Press

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Remember that one time on The X Files

when Mulder brought Krycek around to Skinner’s place

and Skinner was randomly shirtless

and heaps buff

and he beat Krycek up and handcuffed him to his balcony

and told him to “think warm thoughts”?

Well, if you didn’t remember, you do now.

You’re welcome.

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Possible fragments from Tunguska meteorite may solve 100-year-old mystery

It wiped out 2,150 square kilometers of forest, has left meteorologists stumped for more than a century and been the subject of a role playing mystery on Nintendo’s Wii and DS. Now, 105 years after the Tunguska Event in Siberia, Andrei Zlobin of the Russian Academy of Sciences’ Vernadsky State Geological Museum claims to have found the first and only clue to what caused the impact. And as it turns out, it’s been sitting in his lab, unnoticed, for the past two decades.

According to his paper on the find, published at arXiv.org, Zlobin picked up stone samples from the bottom of Khushmo River on his way back from an unsuccessful field research trip to the Suslov depression in 1988, an area where much of the damage at Tunguska is visible. He had dug a series of holes in the permafrost, looking for potential meteorite or comet fragments at depths of 1908 soil levels, but to no avail. On his way back he collected around 100 stones from the riverbed, but failed to examine them until 2008.

When he finally studied them, Zlobin found that three of those stones exhibited signs of melting (one has a particularly glass-like surface with bubbles). They also feature regmalypts on their surface — fractures that occur when meteorites soar at great speeds towards Earth, causing fragments to vaporise off as atmospheric gases rip around them. Although the impact of the hit is estimated to have been 1,000 times more powerful that the Hiroshima bomb, the heat of the impact is not thought to have been hot enough to melt any rocks on Earth’s surface (according to samples taken from trees affected in the area). Hence, Zlobin is claiming the rocks exhibit all the markers of being meteorite fragments. He does, however also assert that the density of whatever hit Tunguska (about 0.6g per cubic centimetre) matches up with density measurements of Halley’s comet’s nucleus, so a comet has not been ruled out. 

Although Zlobin admits there is plenty more work to be done — chemical and isotopic analysis is needed to find out what’s going on inside the three rocks — it’s an interesting find. Tunguska has left the scientific community stumped for over a century for several reasons. Although it’s presumed the impact was the work of a comet or meteorite (some argue an alien being…), the blast occurred in an incredibly remote area of Siberia that was uninhabited and not explored until 1927, when meteorologist Leonid Kulik ventured into the field. He did not unearth any evidence (there were accounts of him finding a similarly glassy stone, but it was lost), and more importantly he was unable to find any evidence of a crater, as has no one since. 

Zlobin’s find will certainly reignite interest in the mystery, but he’s created one of his own in the process. Why would someone who has dedicated much of their career to investigating Tunguska wait more than two decades to study stones retrieved from the area?

L’evento meteorico russo ha sollevato tre domande d’importanza capitale:

1 perché negli anni 80 l’apparato militare sovietico riusciva a sapere nel giro di 3 minuti se in un silos missilistico americano stavano anche solo passando la cera ai pavimenti e invece oggi non si accorge di una sassata simile in arrivo?

2 perché agli uragani, agli anticicloni, agli acquazzoni viene dato un nome idiota mentre alle meteore no?

3 visto che il precedente evento paragonabile a quello di Chelyabinsk era stato a Tunguska, in Siberia, nel 1908, perché diavolo la natura ce l’ha tanto con i russi?
(3 bis: c’entra forse la musica che ascoltano in macchina?)

The Tunguska event

At 7.17 am on the morning of June 30, 1908, an explosion erupted in remote Siberia, ripping two thousand square kilometres of trees from their roots. Called the Tunguska event, it felled over eighty million trees, killed hundreds of reindeer, registered on barometers as far away as England, and made the night skies glow as far away as China.

The region is so remote that the first scientific expedition to the impact sight wasn’t for 19 years, led by Leonid Kulik, and they found no crater like you might expect, just mineral traces and endless felled trees. Even after 100 years, scientists aren’t 100% certain about what happened.

People have come up with all sorts of fabulously impossible explanations—a UFO crash, the annihilation of a chunk of antimatter, a mini black hole, Nikola Tesla’s “death ray”, a visitation by the god Ogdy—but the generally accepted theory is that the Tunguska event was, in fact, a large asteroid. It’s thought that during its plunge down through the atmosphere, the combination of speed, pressure and accumulated heat caused it to detonate 5–10 kilometres up, burning itself up and producing an immense shockwave.

The size of the asteroid is still debated, but it’s the largest impact event on or near Earth in recorded history. On average, an asteroid this size will plunge through Earth’s atmosphere every 300 years.

(Image Credit: Leonid Kulik)

S.B. Semenov, a witness of the Tunguska event of 1908.

"The sky split in two and fire appeared high and wide over the forest. The split in the sky grew larger, and the entire northern side was covered with fire. At that moment I became so hot that I couldn’t bear it, as if my shirt was on fire; from the northern side, where the fire was, came strong heat. I wanted to tear off my shirt and throw it down, but then the sky shut closed, and a strong thumb sounded, and I was thrown a few metres.

After that such noise came, as if rocks were falling or cannons were firing, the earth shook, and I was on the ground, I pressed my head down, fearing rocks would smash it. When the sky opened up, hot wind raced between the houses, like from cannons, which left traces in the ground like pathways, and it damaged some crops.”