The mystery of the Tunguska explosion may have been solved, the real cause was a drifting meteorite phenomenon

The Tunguska event remains the most powerful explosion ever recorded. It released 185 times the energy of the atomic bomb dropped on Hiroshima.

At 7:17 a.m. on June 30, 1908, in the Evenki Autonomous Region of Siberia, a huge fireball tore across the sky, a minute later the ground shook and local residents felt a violent earthquake.

But when people found the explosion site, they were surprised to see that 80 million trees around had been destroyed, covering an area of ​​more than 2,000 square kilometers ^. Compared to similar events in ancient times, the Tunguska explosion took place in a shorter time but was larger in scale, which made it the most famous explosive event in human history, and is considered one of the greatest unsolved mysteries of the 20th century, attracting the attention of countless scientists and the public.

On June 30, 1908, an explosion tore through the calm Siberian sky, suddenly occurring above a remote forest near the Podkamennaya Tunguska River. Under the enormous pressure of the explosion, more than 2,000 square kilometers ^of taiga forest, with an estimated 80 million trees, collapsed to the ground. Scientists believe that the fireball that exploded in the sky that year was between 50 and 100 meters in size. (Photo: CNN).

At first, people speculated that this was the impact of a small asteroid. However, there were no large craters around and no meteorite fragments were found at the site. Apart from a large amount of charred trees, there seemed to be no other obvious signs of what had happened. But the surrounding plants and animals showed signs of radiation.

Years of subsequent research found that tests in these areas detected elements such as iridium and nickel , confirming that these elements were indeed of extraterrestrial origin. 

The expedition team spent years pumping out the swamp created by the explosion, but they failed to find any clues about the incident. Since then, the Tunguska explosion has been a regular feature in the newspapers under the headline 'Unsolved Mysteries.'  Some have suggested that it was the work of aliens, while others have suggested that it was Tesla's 'secret weapon .' Some have even spread rumors that the Soviet Union was secretly developing nuclear weapons at the time.

Later, people put forward a relatively reliable speculation, which is the 'ice meteorite' hypothesis.  According to this theory, only meteorites whose main component is ice can create enormous power without leaving obvious traces after the explosion. However, more than 100 years have passed since the explosion, there are still many different opinions about this hypothesis.

To this day, the Tunguska event remains the most powerful explosion ever recorded. It released 185 times the energy of the atomic bomb dropped on Hiroshima. (Photo: Zhihu)

But in recent years, scientists have been working to solve this centuries-old mystery. In 2020, a team from Russia's Siberian Federal University came up with a radical new explanation: They believe the Tunguska explosion was likely caused by an iron-dense asteroid . And the reason we can't find impact craters and meteorite debris is because it didn't actually hit Earth. 

Instead, it passes through the Earth's surface at extremely high speeds and then returns to space . This phenomenon is called an "Earth-skipping asteroid ." These asteroids that skim the Earth are those that enter the Earth's atmosphere at an angle of less than 10° and have enough speed and mass to escape Earth's gravity. Because the Earth's surface is curved, these asteroids undergo one or more bounces in the atmosphere, much like a stone bouncing across water. In the process, they create tremendous friction and compression, causing their surfaces to glow and releasing enormous amounts of energy.

More than a century has passed, and we still don't know what caused the world-shaking event. Many believe that a meteorite or comet exploding in the sky caused the huge explosion, but we have found very few traces of this supposedly giant celestial body. The event is shrouded in mystery and has stimulated the rich human imagination. (Photo: ZME).

Asteroids drifting around the Earth are not a purely theoretical hypothesis but a phenomenon with real observational records. The most famous example is the 'Great Solar Fireball' event that occurred in Utah, USA on August 10, 1972. In this event, an asteroid about 10 meters in diameter and weighing about 4,000 tons passed through the atmosphere from southeast to northwest at a speed of about 15 kilometers per second, then returned to space. Its lowest point was only 58 kilometers above the ground, lower than some artificial satellites. As it passed through the atmosphere, it turned into a bright fireball, leaving a long trail that was recorded by many cameras and witnesses.

Based on these observations, researchers believe that as the asteroid passes through the atmosphere, it will carry the surrounding air with it to move at high speed, forming a giant air stream. At the same time, the asteroid will strongly compress the air in front of it, causing the air to heat up rapidly. This will cause some of the surface material and surrounding air to be ionized due to the high temperature, becoming a state of charge imbalance.

Scientists believe that an iron asteroid about 200m in diameter caused the Tunguska explosion. (Illustration: Zhihu).

In this case, if the asteroid is fast enough and close enough to the Earth's surface, even if its main body does not directly hit the ground, it can still cause an explosion on the ground. This is because the plasma and air carried by the asteroid will collide and mix violently with the air on the ground, creating a huge shock wave and heat, like a giant bomb. This may explain why we cannot find impact craters and meteorite debris.

With this hypothesis, the next step is to determine what kind of asteroid could cause an effect like the "Big Tunguska". The researchers used computers to conduct a large number of simulations, in which the simulation results closest to the real situation are: an iron asteroid about 200 meters in diameter traveling at a speed of 20 to 25 kilometers per second , reaching its lowest point at 10 kilometers above the ground, then, because the asteroid's speed is enough to escape the Earth's gravity, it continues to increase in altitude and finally returns to space.

Although this explanation is more plausible theoretically, due to the lack of convincing supporting evidence at present, this explanation is only a reasonable speculation and not a definitive answer. Hopefully, in future studies, scientists will be able to find more clues to reveal the truth behind the Tunguska explosion.