Tunguska, 1908: Russia's Greatest Cosmic Mystery

The stunning burning-up of a meteor over Russia on Friday that unleashed a shockwave injuring hundreds of people appears to be the country's most dramatic cosmic experience since the historic Tunguska Event of June 1908.

The Tunguska Event was an explosion that went off in a remote region in Siberia on June 30, 1908, near the river Podkamennaya Tunguska in the north of current Krasnoyarsk region.

Most scientists believe it was caused by a massive meteorite, an asteroid or even a comet although the failure to find fragments from the impact created a mystery that has spawned sometimes endless theories.

The few people closest to the supposed impact area of the Tunguska meteorite were the indigenous Evenki hunters.

Assuming the crater was caused by an impact from space, the body estimated as being of up 70 meters in diameter caused a seismic wave and lit the sky above Siberia for several days.

The sound of its impact was heard about a thousand kilometers away and the overall effect knocked people and livestock off their feet.

However, some theories suggest that there was in fact no rock, because no fragments of it were ever found. One of such theories looks at the possible escape of methane gas from the ground.

The incident remains a source of multiple wilder hypotheses, ranging from an encounter with a black hole, a landing of a UFO or experiments by the celebrated physicist and inventor Nikola Tesla thousands of kilometers away in New York.

The event still tickles the imagination of Russians and is a tourist attraction for those bold enough to make it to the Podkamennaya Tunguska area.

Black and white early photos taken around the supposed impact area show fallen taiga, which the first explorers measured to spread out from the epicenter for up to 30 kilometers.

The remoteness of the swampy Tunguska area, and the fact that Russia was enveloped in several wars and the Bolshevik Revolution in the early 20th century, meant that only a limited number of people managed to travel there.

The first scientist who ventured to look for the meteorite was mineralogist Leonid Kulik, who made several expeditions, starting in 1927, scavenging for metal remains over hundreds of kilometers in extreme conditions precipitated by lack of money and constant illnesses in the team.

Despite digging and draining scores of apparent craters, nothing resembling a meteorite was recovered.