On June 30th 1908, there was an explosion in central Siberia.  That fact alone may not seem particularly remarkable, but when other aspects of the explosion are taken into consideration, you may wonder how an event so big on a global scale could remain a total mystery, even to this day.

Even the bombing of Hiroshima was small by comparison.  In fact, whatever caused the Siberian explosion was 1500 times more powerful.  Small wonder then that the shockwave it created went twice around the Earth before finally subsiding.

For about two months after the blast, the Northern hemisphere experienced incredible changes to the night time skies.  For instance, it was then quite possible to take clear photographs at night – without the aid of a flash; people could read before going to bed, without needing to switch on a light to do so; and the skies at midnight were composed of colours so amazing that they put the aurora borealis to shame.

Despite the enormity of the event and its after effects, mankind had luck on its side that day.  Even though thousands of villagers in the region were believed to have lost their lives in the disaster and thousands of square miles of Tunguskan forest were similarly destroyed in a matter of seconds, if the explosion had occurred elsewhere in the world the death toll could easily have stretched into the millions.

It seems hard to believe that an explosion violent enough to be heard up to 5000 miles away, and felt even further away than that, should remain unexplained even now, almost a hundred years later.  However, due to the remote location of the event, the world knew little of it for some years.

Local reports and eye witness accounts appeared in newspapers at the time but only reached a worldwide audience in 1921.  At that time a Russian scientist called Leonid A Kulik came across the reports and began to investigate what had happened thirteen years earlier.

So at last the cause of the Northern hemisphere’s strange and wonderful night time displays had been discovered.  But an expedition to the devastated area merely yielded more questions when the Russian Academy of Sciences finally gave Kulik permission to visit the site of the blast in 1927.

The obvious initial idea was that a huge meteorite had caused the devastation.  However, when Kulik arrived in the Tunguskan region he soon realised this theory did not fit all the evidence he saw there.

There was one essential difference between theory and reality.  Meteorites habitually leave a crater to mark the point of impact yet there was no such crater to be seen.  In fact, the piece of land which Kulik pinpointed as being the centre of the explosion was far from crater like in appearance.

The vast majority of land affected by the blast had been flattened; strong and sturdy trees had been felled like twigs.  Yet at the centre of the blast area the trees were still standing – charred, blackened and dead, but still upright.

This led Kulik to suppose that whatever had caused the devastation had exploded before making contact with the ground.  This hypothesis tied in with eye witness reports and provided confirmation that a meteor could not have been the culprit.

Further aspects of the event continued to puzzle Kulik.  Firstly, the eye witness reports which had helped to rule out the meteor theory also seemed to contradict any other natural cause such as a comet, black hole or asteroid.

Also, people living in the Siberian village of Nizhne-Karelinsk had seen the mystery object change direction before finally exploding.  Such behaviour can be explained only in one way – there must have been an intelligent source responsible for manoeuvring the object.

Secondly, the after effects produced by the blast were unlike any that humankind had seen before.  Scientists were at a loss to explain how several new species of plant and animal life came to be found in the area several years after the blast.  Similarly, they were unable to discover why the previously healthy people of the region began dying at unusually early ages from undiagnosed diseases, and why animals began to develop strange burns on their bodies.

Today, nearly a hundred years of human advancement has finally provided us with at least some of the answers to questions that puzzled Kulik and his fellow scientists.  After atomic bombs were dropped on Hiroshima and Nagasaki, certain parallels could be drawn when comparing nuclear tragedies to what had happened years earlier in Siberia.

One identifying trait of the atomic bomb was that it exploded in mid-air rather than on impact.  As with the trees in the Tunguskan region, the buildings situated at the centre of the nuclear explosions remained intact, though badly scarred, while everything in the surrounding area was flattened.

Furthermore, the radiation fallout created by an atomic bomb leads to radiation sickness, greatly reducing life expectancy in those who survive the initial blast, as well as causing severe burns on the body.  The huge amounts of radiation were also responsible for the new species of plants and animals that appeared in both Hiroshima and Nagasaki some time after the bombs were dropped.

At this point it seems obvious to assume the Siberian explosion was caused by an atomic bomb.  After all, many of the characteristics – including the telltale mushroom cloud – were present.  Yet the Siberian explosion occurred decades before the world entered the nuclear age.

But if the source of the Siberian disaster was of a nuclear nature, surely there is only one other place it could have come from – outer space.  So did a spaceship from another, more advanced planet make a fatal error and explode over planet Earth all those years ago?

This suggestion may seem far fetched yet there is some curious evidence that may offer support to the supposition.  Soviet scientists discovered two things that cast a shadow over any natural disaster theory.  Firstly, their studies of the Tunguskan site led them to estimate the object weighed more than 50,000 tons, and secondly, the area affected by the blast was triangular in shape.

There have been sightings of UFOs which are similar in shape, if not size.  If it was an alien ship which crashed that day, the planet it came from would have learned from the tragedy, just as we learn from plane crashes, and developed smaller, more manageable, safer craft to pilot.

However, despite all the theories, it seems that we will never know for certain exactly what happened on June 30th 1908.  If a similar event happened today, would we be any better equipped to explain it now than we were then?

Perhaps not, because although some strange metal fragments were found at the site and modern testing has revealed that soil samples contained particles which do not exist on Earth, no sizeable debris was discovered.  Whatever the object was (and anything or anyone inside it), it was swallowed up in the huge fireball created by the explosion.

And so, it seems, was the solution to one of mankind’s greatest mysteries.