At 7:15 a.m. on June 30, 1908, something exploded in the sky above Tunguska in what is now Siberia. Normally, an explosion doesn’t make national or international news—but, when the explosion is estimated to be between 10 and 15 megatons that topples 60 million trees over an area of about 2,150 square kilometers, people have a tendency to notice.

The Tunguska region was and is rather isolated and not well populated. Had this explosion occurred a few hours later, scientists figure that it would have occurred over Europe and resulted in the massive loss of human life—to the point of altering the human race.

The first recorded expedition for which the records remained occurred in 1921. Leonid Kulik went to the Tunguska River Basin to do some surveying for the Soviet Academy of Sciences. After talking with some of the local people, he surmised that a meteor had struck and convinced the Soviet government to fund an expedition to search for meteoric iron, which would aid the Soviet industry.

In 1927, Kulik and his team returned to the River Basin to explore for the crater to collect the minerals. They found about 50 kilometers of scorched trees, but—much to their surprise—no crater. The trees near what they assumed to be “ground zero,” were standing upright, their bark and branches stripped away. The other trees were knocked over away from the center.

Kulik went back to the location over the next ten years, finally discovering what he called a “pothole” bog that he thought was the crater. After draining the bog and doing some tests, he discovered his idea to be false. In 1938, he ordered aerial photographs taken of the region. The pattern of the toppled trees was in the shape of a large butterfly. Soil samples taken, however, showed no high levels of radiation—seeming to rule out the theory of a nuclear explosion.

With no crater and no radiation, Kulik and other scientists began to speculate as to the cause of the blast. They knew it happened between 3 and 6 miles in the air, and had to be extremely massive to cause the damage it had caused. In the ‘50’s and ‘60’s, chemical analysis on glass spheres found at the site revealed a high concentration of nickel and iridium, both of which are present in meteorites, leading to a theory that the blast was extraterrestrial in nature.

The leading belief is that the blast was caused by a “stony comet” or “stony meteorite.” The idea behind this belief is that the pressure exerted upon the object entering the Earth’s atmosphere had been greater than the pressure holding the object together. Therefore, the pressure caused the object to break apart, causing the thermal and blast damage of the area. To this day, the mystery remains. Other theories on the cause range from a simple meteor crash to aliens, nuclear testing, a Nikola Tesla experiment, anti-matter, and more. Recent testing and discoveries seem to have located a possible crater in the form of Lake Cheko. The lake is conical in shape, consistent with a crater, and seems to be about 100 years old—which would put it at the correct time frame for the blast. Experiments are still on-going.

For more information or to view my sources, visit The Tunguska Event and Wikipedia.