The Mystery of the Tunguska Disaster - What Could Cause It?

 The event of great force took place on June 30, 2008 on the Podkamienna Tunguzka river in central Siberia. Direct witnesses saw or felt its impact from miles away. However, the object did not leave any unequivocal traces, which contributed to the creation of many more or less credible theories.

The place where the event took place was tens of kilometers away from any human settlement. The closest surviving account comes from the Evenks who lived 30 km from the epicenter. The nearest settlement was located 70 km away.

It was a dry day, the beginning of a short Siberian summer. The sky was clear, only in the distance appeared a luminous tube-shaped object (others spoke of a sphere) and a small cloud visible in the same direction. The object was in the sky for about 10 minutes. As it neared the forest, it became less and less clear. Black smoke appeared before it touched the ground. Eventually, it hit the woods and there was a thudding or firing noise (but not lightning) all around. Buildings shook. Tongues of fire burst from the cloud.

The cloud appears only in some descriptions. Most saw a fireball or a cylinder-shaped object. The roar of many compared to shots from large-caliber cannons. Some also added that the earth was shaking. Some windows within 200 km of the glass cracked. You can guess how the inhabitants of the Siberian villages of the early 20th century reacted to such an unusual event. Many believed it was the end of the world.

At first glance, it seems obvious that this is a particularly large meteorite. However, there are many details that put this most popular theory into question.

The main problem was the relationships themselves. What the newspapers reported usually rationalized the event as a meteorite strike. Some even described that the local people observed the celestial body after the fall. At least some of these accounts are questionable. More systematic research began in the 1920's. The information collected did not indicate a usual large meteorite impact:

1. Anomalies in the sky had appeared a few days earlier and were observable even in the British Isles,
2. The celestial body seen by the witnesses did not have a characteristic smoky tail. It is described as a spherical or cylindrical object - white, yellow or red,
3. The rainbow effect was visible behind the falling object,
4. The body exploded at a force of 40 to 50 megatons (about 3,000 times greater than the bomb dropped on Hiroshima almost 40 years later). The Evenks closest described this moment as the appearance of a second sun - reminiscent of an atomic explosion,

These and other details of the event raise doubts about the falling meteorite theory, even if it were very large and had a specific composition. (cf. Rubstov V.V., 2009: pp. 2-3) The explosion was explained by the air resistance that caused the celestial body to explode before it touched the ground. However, there were other unexplained remnants.

The lack of interest of scientists right after the event is astonishing. The content was mostly broadcast by local newspapers. Some journalists have added fantastic stories of their own. For example, Alexander Adrianov in "Life of Siberia" of July 2 described the story of a train that stopped in front of the Filimonovo station. Initially, the passengers could not get close to the meteorite because it was too hot. When it cooled down, it was examined in more detail by local residents. However, all indications are that Adrianov invented at least half of the stories. Based on this account, later scientists tried to find the meteorite in question.

The main researcher was Leonid Kulik, a member of the Russian Academy of Sciences. He went to the vicinity of the event for the first time in 1921. The initially collected reports clearly showed that it must have been an iron meteorite. He designated a large area with hectares of fallen trees as the site of the collapse of the facility. The problem with Kulik was that he was a meteorite specialist. The stories convinced him that this was what he was dealing with, and he considered every anomaly in the area to be remnants of an impact by a cosmic object of this type. So much so that he mistook thermocars (landforms left over from melted ice) for craters after a meteorite impact.

Despite the efforts of this and other scientists, no traces of the meteorite itself or its fragments were found. The 1927 expedition in general found that at the true epicenter of the impact the forest was still standing and there was no post-impact crater.

It became clear that the event could not be easily explained. So various theories began to emerge. Not all strictly scientific.

In the 1930s, the most popular theory was that the destruction must have been caused by a comet that exploded on the Podkamienna Tunguzka River. The comet rapidly heated up as it entered the atmosphere, causing an explosion. As it was composed of ice, it evaporated during the explosion and left no traces of its presence. However, the force of the blast was capable of knocking down the forest, and the melting ice as it passed through the atmosphere caused a glow - seen in Europe and Asia. Melting ice water would even confirm the observed rainbow effect around a falling object. This theory is one of the acceptable and remains in the pool of possible explanations to this day.

In 1946, a Soviet science-fiction writer, Alexander Kazanceev (not to be confused with an émigré activist of the same name), gave a completely different hypothesis. Perhaps the object that crashed over central Siberia was an alien ship? After World War II, it was not only in the United States that people became interested in UFOs. It is no coincidence that it was then that the hypothesis was created, which started a long-term discussion among people interested - professionally or as amateurs - in the Tunguska catastrophe.

Kazanceev's hypothesis was not only the impetus to investigate more closely what actually happened over central Siberia. She became an inspiration for many science fiction authors. In this way, Podkamienn Tunguzka became something like the Soviet counterpart of Roswell - the alleged site of an alien ship crash in New Mexico. And even the opposite - the fame of the Tunguska crash as a UFO landing site already had many supporters, when a similar role began to be assigned to its American counterpart.

It is worth adding that at that time Soviet astronomers insisted on the version with the meteorite. They even stated that the crater was indeed formed, but since no one visited the site for the first 12 years, it was flooded and overgrown with marshy vegetation. The comet theory still had its support. For example, Kirill Florensky, the leading geochemist of research expeditions, stated unequivocally that the comet is the ultimate and best solution to the Tunguska mystery. The year was 1961, and neither his position nor anything else would be the "final" for the next few decades. To this day, it is not, but the theories accepted today have introduced another suspect.

It was not actually a huge meteorite, but microscopic iron fragments contained in the rocks at the scene. It was not until 2013 that Ukrainian scientists discovered them, when they examined the rocks that had been collected for a long time. This time under an electron microscope. It has been found that they may be the remains of a large object that broke into tiny pieces during a massive explosion. So the meteorite that Leonid Kulik had been looking for so strenuously almost a century earlier could have been there all the time. The technology of that time simply did not allow him to be noticed.

This research is accepted in many official sources as the best and currently most official explanation for the whole event. This does not mean that there are no others.

Interesting, if a bit chilling, is one of the latest hypotheses proposed by researchers from the University of Krasnoyarsk in 2020. Briefly, they suggest the asteroid bouncing off the earth's surface (which caused the phenomena described above) and then its return to solar orbit.

This hypothesis was proposed as part of research into the possible reaction of similar celestial bodies to the earth's surface.

The asteroid is not a small meteorite, but a large piece of celestial body. Quite large from the point of view of tiny earthlings, anyway. If such a body did collide with our planet, it would cause much worse damage than overturning a piece of Siberian forest and some accompanying special effects. However, a team of Russian scientists considered the possibility of "safe" entry of such an object into our atmosphere.

The Tunguska disaster may be one of those mysteries that will never be fully solved. Nevertheless, these and other unusual phenomena make us discover new secrets of the Earth and the Universe.

Bibliography:

• Victor Kvasnytsya et al., New evidence of the meteoritic origin of the Tunguska cosmic body, in: Planetary and Space Science, vol. 84 (August 2013), pp. 131-140
• Daniil E. Khrennikov, On the possibility of through passage of asteroid bodies across the Earth's atmosphere, Monthly Notices of the Royal Astronomical Society, Volume 493, Issue 1, March 2020, pp. 1344–1351
• Vladimir Vasil’evich Rubtsov, The Tunguska mystery, New York 2009
• Е. Л. Кринов, тунгусский метеорит, in: http://tunguska.tsc.ru/ru/science/1/2, accessed on 07/09/2009