Tunguska event mystery

100 years ago, a terrible explosion ripped the dawn sky over the swampy taiga of western Siberia, leaving a riddle to this day still a mystery.

A glimmer of light crossed the sky, followed by a shockwave of energy from a thousand atomic bombs that flattened 80 million trees in an area over 2000 km ² .

Evenki travelers still recounted how the explosion blew their homes and animals into the air. In Irkutsk, 1500 km away, stratigraphic sensors recorded phenomena that seemed like an earthquake. The fireball was so big that one day later, Londoners could still read newspapers in the night sky.

The cause of the Tunguska event - named after the Podkamennaya Tunguska river near where it happened - is still in at least half a dozen hypotheses.

The biggest hypothesis is that a rock after traveling in space for millions of years ended the journey to Earth exactly at 7:17 am on June 30, 1908.

Even the most enthusiastic supporters of the sudden collision hypothesis also know there are still many loopholes. They tried to find the answer, believing that this would strengthen the defense against threats like Tunguska in the future, an event that experts say with an average frequency of 1/200 years until 1/1000 year.

About 80 million trees fell after the Tunguska explosion.Photo taken in a survey from 1927. (Photo: astro.wsu.edu)

According to Nature's scientific journal, 'Imagine a meteorite suddenly plunging into a land that is not like Tunguska and other meager desert areas on earth today, that land has living people. '

If the culprit is a rock, the choices will lie between a meteorite - debris knocked out of the orbit between Mars and Jupiter by default to the earth, and a comet - the ball filled primitive, icy materials hover around the solar system.

Comets move at a much greater speed than meteorites, meaning they release greater kinetic energy when collided. A small comet will have the impact force equivalent to a larger meteorite.

However, after many searching efforts, no fragments were found during the Tunguska event.

According to Italian researchers Luca Gasperini, Enrico Bonatti and Giuseppe Longo, finding a piece is also important because it will enhance our understanding of the danger of near- Earth objects ( Near Earth Objects). - NEOs ).

When a new meteorite is discovered, its orbit can be used to predict collisions many years later in the future. Comets have a much smaller amount than meteorites but are more worrisome, as they are an unknown entity.

Most comets have not been discovered because they take decades or even hundreds of years to spin around the sun and surpass our faces. As a result, any comet at risk of crashing into the earth may suddenly appear in the dark and give us little time to react.

Gasperini's team writes in Scientific American that 'If the Tunguska event is actually a comet, it is unique and not just an important case in the classified phenomenon. . On the other hand, if a meteorite really exploded in the Siberian sky that June morning, why didn't anyone find a fragment? '

NEO experts are also not sure about the size of the object.

According to the judgment, based on the scale of ground destruction, it has a size of about 3m to 70m . They all agreed that the object, heated by friction with the atmospheric molecule, exploded away from the ground - from a few kilometers to 10 kilometers.

But there is a fierce debate about whether any debris hits the ground.

This is extremely important. If the Tunguska event happened again, the Earth Guardians had to choose whether to divert its direction or let it explode in space, with the risk that an object of a certain size could exist later. when burning in the atmosphere and colliding with our planet.

Lake Cheko.(Photo: University of Bologna)

The Italian trio believes that the answer lies in an oval lake, called Lake Cheko , located 10km from the collision location. They planned to return to Lake Cheko hoping to find an object of the same size 10 meters below the funnel-shaped bottom of the lake that reflected the ultrasound.

But what if the reason is not comet or meteor? A new hypothesis stirred up in New Scientist.

Lake Cheko has no common circle of a collision hole, and no extraterrestrial matter is discovered, meaning 'the cause of the earth itself' , according to Wolfgang Kundt - physicist. at the University of Bonn, Germany - told New Scientist.

He believed that the Tunguska event occurred due to the release of 10 million tons of methane rich gas in the earth's crust. Evidence of the same destructive exhaust can be discovered at Blake Ridge, the seabed outside Norway: a 700-square-kilometer "hole" .