Skip to main content

What Was the Tunguska Event?

Leonard Kelley holds a bachelor's in physics with a minor in mathematics. He loves the academic world and strives to constantly explore it.

On June 30, 1908, at roughly 7:14 A.M. local time an explosion in Siberia leveled over 2,000 square kilometers of forest and was registered as far as England. This was known as the Tunguska Event, and they happen way more periodically than we like to think. But for years the event was shrouded in mysteries as to what it was.

Analysis

It took over a decade to actually get a scientific expedition to the site due to political upheavals in the country preventing such a venture. But one there, scientists were amazed to find over 40,000 trees knocked down in a circular radial pattern (Chyba 41, Tedesco).

Based on the number of trees that were knocked down (over 2000 square kilometers) and the level of scorching seen (100 square kilometers), scientists estimate that the object which caused this destruction gave off 10-20 megatons of TNT of energy which was released about 8 kilometers above the ground. But it was difficult to confirm any of this, for no fragments of the object were found not a crater either (Ibid).

This has led to some wild speculation over the years as to what could cause that. Some have proposed it was a mini black hole passing through the Earth, but why is there no trace of its path through another piece of the Earth? If it was an antimatter asteroid, it would have been way more devastating than what really happened. And UFOs are not defensible as a hypothesis because there is no confirmation or denial possible with it (Chyba 42-3).

Swamp gas is really the only alternative to a celestial origin, and the material is produced at the sight. But if the explosion was 100% efficient (which is challenging), then 60 billion cubic feet would be needed and that is just a very, very, unlikely amount to be just floating about and near the same place (Ibid).

The impact site.

The impact site.

Therefore, the asteroid or comet path is the best option. Earth-crossing objects move at about 40 to 60 kilometers a second and taking that along with the blast information points to an object about 60 meters wide. Comet proponents point out the numerous noctilucent clouds over Europe shortly after this, possible from a sudden increase in ice crystals in the upper atmosphere left by the disintegrated object (Chyba 43, Tedesco).

However, we know asteroids end up impacting us quite frequently, so based on the numbers it should have been an asteroid. But the $64,000 question is how do you get an object like either of those to explode and leave no traceable fragments for you to find? Well, you bring in computers to help (Ibid).

Christopher Chyba implemented computer models to give insight as to what might have happened. Some rocky-stony object fell apart and vaporized all within 0.1 to 0.2 seconds. This was all a result of entering Earth’s atmosphere, which created a huge amount of pressure on the front of the object as it encountered severe air resistance and practically no pressure in the rear as a result of the vacuum being generated from the displaced air. It got to the point where the structural integrity of the object falls apart and it spreads out like a pancake (Chyba 44, Tedesco).

This increases the surface area which increases drag until the object suddenly stops above the ground. All that energy has to go somewhere and so the remains vaporize, sending a shock wave outward and scorching near the epicenter from the high temperatures involved. Nowadays, it is accepted that the object blew up at 5 to 10 kilometers above the Earth’s surface. And it isn’t like we don’t have recent examples, on a smaller scale, to demonstrate the validity of these ideas (Ibid).

Simulation results of what objects do on their way to Earth.

Simulation results of what objects do on their way to Earth.

Revelstoke

On March 31, 1965, in British Columbia and Alberta a meteor exploded 30 kilometers above Revelstoke. A pressure wave from it was recorded as far away as Boulder, Colorado, helping scientists narrow down the energy of the event at about 20 kilotons of TNT, an atom bomb blast worth. Yet amazingly, no destruction was visited on the ground below, and also no crater was spotted (Chyba 40).

So how do we know this was a meteor? Two weeks after the blast, small fragments were found on top of 6 feet of snow near Macpherson Lake. The fragments themselves were small, on a millimeter scale, and the total amount retrieved was less than a grams worth. But it was enough to identify the object as a carbonaceous chondrite (Ibid).

How deadly can it be?

How deadly can it be?

Chelyabinsk

And who could forget the recent meteor that streaked the skies across Chelyabinsk, Russia on February 15, 2013? It proved clues to help us understand Tunguska even better. So much footage of it was taken by dashcams and the plethora of witnesses gave scientists ample data to work with, which helped them identify the meteor as “a stony asteroid the size of a five-story building that broke apart 15 miles above the ground” (Anderson).

The resulting shockwave from the disintegrated object yielded a shockwave comparable to a 550-kiloton bomb. So, to put this into context, the Tunguska object was about 3 times bigger, and look at the damage this smaller one did. It’s easier to appreciate the power of these objects, and it hopefully puts to rest the enigma of the Tunguska Event (Ibid).

Works Cited

Anderson, Paul Scott. “When the sky exploded: Remembering Tunguska.” Earthsky.org. EarthSky Communications Inc., 30 Jun. 2020. Web. 23 Apr. 2021.

Chyba, Christopher. “Death from the Sky.” Astronomy Dec. 1993. Print. 40-4.

Tedesco, Edward F.. "Tunguska event". Encyclopedia Britannica, 23 Jun. 2020, https://www.britannica.com/event/Tunguska-event. Accessed 23 April 2021.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2022 Leonard Kelley