Whoever looks at the Tunguska plains in Russia nowadays is far from imagining what happened there a hundred years ago. On the 30th of June, 1908 an explosion of a tremendous intensity shook the ground. At the time, the happening went by almost unnoticed internationally, maybe because of the isolation of the region, located at the very heart of Siberia. It's likely that explorations were made in the place, but the turmoil of the years to come (WWI and the Russian Revolution, followed by the Civil war) must have erased any data of the happening. We had to wait until 1920 for a consistent scientific expedition to be sent to Tunguska, led by Russian mineralogist Leonid Kulik. We own a large portion of the knowledge we have today about this phenomenon, even though it's still a bit clouded, to this scientist.
The first expedition began in 1921 and, for over a decade, other followed. Kulik heard and registered the accounts of the region's inhabitants. They mentioned seeing a bright blue trail crossing the sky, a very bright flash, the roar of a thunder and the shock waves that pounded the ground and shattered the glass. For the several nights that followed the sky was bright and sparkled. The accounts, however, varied from one person to another, when it came to the sequence and duration of the events.
Kulik also tried to fix the limits of the area of the event, through the destruction of about 80 million trees in a radius of 50 km from a central point where the force seemed to come from. An aerial observation revealed that it actually had the shape of a butterfly with an area of 215 000 acres completely destroyed. However, not a single sign of a crater was found.
The observations made by Kulik led him to concieve a theory that remains, to this day, the most consistent, in spite of the numerous speculations that have come up: the explosion of a meteorite or an asteroid a few kilometres from the ground. Images taken recently account for a region that hasn't completely recovered its normal look, but the pictures taken on Kulik's expeditions were the only testimony of a devastated environment, that had never been seen before.