Event details
At about 7 a.m. on June 30, 1908, more than 100 years after the current explosion over the Evenki Autonomous Region of what is now Siberia, Russia, exploded. The explosion occurred near the Tunguska River, and the event is also known as the Tunguska Explosion.
According to reports at the time, in the morning, locals observed a huge extremely bright fireball across the sky, and a few minutes later, a strong light illuminated the entire sky, and soon the strong shock wave generated by the explosion shattered the window glass within hundreds of kilometers nearby, and people in the distance also observed the mushroom cloud phenomenon.
Mushroom clouds are only produced when a higher-energy explosion occurs, and the most typical scenario is the atomic bomb explosion, and people in the distance can see the mushroom cloud, indicating that the energy released by the explosion is very large.
In addition to the mushroom cloud, the seismic waves from that explosion were also monitored by the seismic monitoring point. In 1975, Ali ben Menachem, a seismologist at the Weizmann Institute of Science in Israel, analyzed data on Tunguska seismic waves and concluded that the energy released by the Tunguska explosion was about 20 million tons of TNT equivalent.
More than a decade after the Tunguska incident, the Ussur Academy of Sciences organized an expedition led by Kulik to investigate the incident. The investigation found that the explosion caused great damage, about 80 million trees within a radius of 26 kilometers were burned and fell, the roots of the fallen trees were facing the heart, and the trees in the center of the explosion were not completely fallen but were scorched. The atomic bombs of Hiroshima and Nagasaki in Japan exploded high in 1945, and the bombing buildings there did not completely collapse.
The huge shock wave also raised large amounts of dust, which even rose to the outer layers of the atmosphere and reflected part of the sunlight, and in the days after the explosion, the night sky in parts of Europe and Asia was like day. According to observations from the Smithsonian Observatory and Mount Wilson Observatory in the United States on the other side of the Atlantic at the time, the transparency of the atmosphere was reduced by at least a few months.
These phenomena are similar to the effects of the explosion of super-yield atomic bombs, such as the Tsarist hydrogen bomb. In 1908, before the invention of the nuclear bomb, what was the cause of the Tunguska explosion?
The mystery of the Tunguska Explosion
There have been many opinions about the cause of the explosion, including some bizarre ideas, such as some people who believe that the explosion was caused by Tesla's experimental wireless transmission technology, and some people who think that it was caused by the disintegration of the explosion of an alien spacecraft...
At that time, people saw a fireball streaking across the sky from south to north, which was supposed to be formed by the friction of the atmosphere when aliens invaded the earth and burned. For aliens, in addition to alien spacecraft, the most likely are small bodies such as asteroids or comets.
When small bodies break into the Earth's atmosphere, the speed can reach tens of kilometers per second, and friction with the atmosphere when crossing the atmosphere will produce high temperatures of tens of thousands of degrees Celsius, and the material on small bodies will be ablated and stripped away by high temperatures, forming a fireball with a tail. If the diameter of the small object is relatively large, the small body will not be completely burned, and the remaining debris will crash into the ground, forming a crater, and possibly leaving meteorite fragments.
If the event was really caused by a small body impact, it is reasonable to say that it would leave craters or meteorite fragments, but they have not been found in the Tunguska region. However, scientists have found elemental anomalies in the area around Tunguska, where some trace elements in the soil are significantly higher than in other regions, and these trace element anomalies cannot originate from the earth itself, but may only be related to small extraterrestrial bodies. It seems that the Tunguska event is indeed very likely to be caused by small bodies, and the entire small bodies should have exploded and disintegrated directly at high altitude.
Scientists said that when the small celestial body crosses the atmosphere at a supersonic speed, in addition to friction with the atmosphere at high speed, the atmosphere in the forward direction will also be compressed, so that the forward direction will bear huge pressure, but the pressure behind is very small, if the material composition of the small body is relatively loose, under the action of huge uneven pressure, it will explode and disintegrate at a high altitude, or crush the bone, or split into several small fragments, making it difficult for people to find its figure after the fact.
According to scientists, the small object was at least tens of meters in diameter when it exploded and disintegrated at a height of several thousand meters above Tunguska. Because of the complete disintegration, it is difficult to find large meteorites.
Threat from small extraterrestrial bodies
With the deepening of research, scientists have found that the impact of such small bodies has often occurred in the history of the earth, and there have been several larger small body impact events that have even led to mass extinction events.
65 million years ago, the dinosaurs that dominated the earth suddenly disappeared from the earth, and scientists believe that this should be an asteroid with a diameter of thousands of meters that hit the earth at that time (the impact point is located near the Yucatan Peninsula in central America), which led to the extinction of the dinosaurs.
In fact, there have been many small body impacts in human history, and some losses have been caused, such as the celestial fall in the Chelyabinsk oblast of Russia.
On February 15, 2013, a small object accidentally broke into the Earth and disintegrated while crossing the sky over Chelyabinsk Oblast, causing a strong shock wave that caused hundreds of houses in Chelyabinsk Oblast to break windows and injure thousands of people. Afterwards, scientists said the small object was about 15 meters in diameter and had an explosion yield of about 500,000 tons of TNT.
There is an asteroid belt between the orbits of Mars and Jupiter, and it is estimated that about 500,000 asteroids of varying masses are gathered in this area, and many of the small bodies that collide with Earth originate from this. At the beginning of the solar system, it may have been possible to form a planet here, but it died under the strong gravitational influence of Jupiter.
Generally speaking, the probability of a larger object colliding with the earth is relatively small, but human beings cannot bear this risk, because once such a small object with a diameter of thousands of meters collides with the earth, especially into a densely populated area, the loss caused by it is quite huge.
In the near future, the small objects of tens of meters in diameter in the Tunguska event may break into the earth and cause damage. Therefore, we must be on the defensive and closely track the movements of small objects that have a high probability of crashing into the Earth. One day in the future, humans may really need to go into space to deflect the orbits of small bodies that may crash into Earth.
Okay, that's it, pay attention to me, we'll see you next time.