The apparent explosion of a small meteor over Siberia early on Friday was not the first time that that part of the world has had a too-close encounter with a space rock. The region was the scene of what is believed to be the largest space-related explosion in human history, 105 years ago.
The Tunguska Event, as it is known, occurred the morning of June 30, 1908, in a largely uninhabited forested area near the Podkamennaya Tunguska River in central Siberia. The site is about 1,200 miles northeast of Chelyabinsk, the Siberian city where some of the damage and injuries occurred Friday.
Scientists believe that an asteroid was the culprit, traveling in a northwesterly direction and exploding at the altitude of a jetliner, about five miles. Various estimates of the size of the object have been calculated over the years; recent calculations suggest it was relatively small, perhaps less than 100 feet in diameter. It's been estimated that the explosion was as powerful as a medium-sized hydrogen bomb, and at least several hundred times more powerful than the atomic bomb that was dropped on Hiroshima.
The airburst flattened tens of millions of trees over an area of about 800 square miles. Among the few eyewitness accounts there were reports of windows breaking and trees snapping 40 miles away. There are no accounts of injuries.
Field expeditions in the remote area in the 1950s and '60s determined from the direction of tree falls the precise location of the blast. The pattern of destruction on the ground was irregular, with fewer trees flattened in front of the blast site and more to the sides. Experiments in the 1960s showed that this was due to the interaction of two shock waves: one caused by the flight of the object, the other by the explosion itself.
The event also produced a nighttime glow in the sky that persisted for several days and could be seen across Europe and in Britain, about 3,000 miles from the site. Later experiments, including some conducted aboard the space shuttle in the last decade, suggest that this glow was due to clouds created as water from the object entered the upper atmosphere. Those findings, in turn, point to the object being a fragment of an icy comet rather than a meteor, but the issue is still the subject of much debate.
Tunguska Explosion 30 July 1908science
This article originally appeared in The New York Times.