h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I agree with the Alien theory but that is because I do not want to belive that Humans are the only inteligent lifeforms in the universe. It could have been enything from a peace ship to a cruise liner, cargoship or even a warship. If it was an alien ship we will never know. I dont like to think that the antimatter theory stands. However what makes antimater viable is that antimatter is very powerful. A pea sized globule of anti-hydrogen could create the devastation of a modern day nuclear weapon and the blast is most probably nuclear. If a nuclear bomb detonates its blast effects radiate in a circle however at Tunguska the blast pattern was a butterfly shape. After experimenting physicists said that this blast pattern was created by a moving object traveling at an angle of 60 degrees to the horizontal. so this supports the alien theory. if you were a pilot would you try to land or collide at 90 degrees to the vertical? The pilot was trying to pull up but unfortunatly disaster struck.

I disagree with the alien theory - but for reference, here is a contemporary report on the blast - as seen from England
"It was in the north east and of a bright flame-clolour like thelight of sunrise or sunset. The sky for some distance above the light, which appeared to be in the horizon, was blue as in the daytime, with bands of light cloud of a pinkish colour at intervals. Only the brightest stars could be seen in any part of the sky, although it was almost a cloudless night. It was possible to read large print indoors and the hands of the clock were quite distinct. I have never at any time seen anything the least like this in England and it would be most interesting if anyone would explain the cause of so unusual a sight
(A letter to the Times from Katharine Stephen of Godmanchester on Thursday 2 July 1908)

As far as I'm aware, the agreed facts are that there was an explosion, and from the blast pattern, and lack of impact cratering, it would appear that the explosion must have been an airburst, probably from an object or objects moving on a non-vertical trajectory.

I understand that the area had been checked for traces of radioactivity, but none had been found, and from what I'd read, the witness accounts mentioned a bright object moving through the sky and then an explosion. I don't remember specific references to saucer shapes, but then, 'saucer shaped' can cover anything from linear through elliptical to circular, depending on perspective.

As far as I can see, the suggested trajectory of the object fits a natural object as well as it does a spaceship. I'm uncertain about the 60 degree to the horizontal figure - to me that does seem a rather severe angle for a deliberate entry, but I'm no alien spacecraft expert.

The size of the blasted area requires a large explosion, but I'd suggest that the source of this explosion can only be consisdered as 'probably nuclear' once natural causes have been ruled out, or some evidence is provided in support.

The similarity between the blast patterns of Nagasaki/Hiroshima and this stem from the fact that they were all massive air-burst explosions - nuclear explosions don't have a different shape than non-nuclear explosions.

My prefered theory is of comet impact, as a comet (mostly ice) is much less dense than a meteorite (mostly iron) so would not make it through the atmosphere but rather would explode in the dense part of the atmosphere.

The fact that a comet travels much faster than a meteorite means that a smaller commet could produce a much larger explosion, and the teardrop shape of a commet could be described as "saucer shaped".

Of course, the possibility that little green men travelled all the way here, dropped a nuclear weapon in the middle of nowhere and dissappeared for a century should not be lightly dismissed

I'd guess the probably nuclear would refer to the fact that to generate such an explosion would be most likely nuclear.
I always thought that it was supposed to be a meteor explosion. Whilst not an extiction level event it was good that it happened over a sparsly populated area as if it happened over a city then it would be catastrophic.
The other main area where a supposed meteor strike is just off the yukatan peninsular. This is thought to be an extiction level event at the cretateous/tertiary boundry, the one which finished off the dinosaurs apparently.

Regarding the non-circular blast, and temporarily ignoring topographic effects (blast shadows from hills, etc.), I was wondering, if a horizontally fast-moving nuclear device were to detonate in mid-air over level ground, how assymmetric would the effects be on the ground be.?

Presumably, the damage from radiation would be roughly symmetrical, but would the shape of the blast waves in the atmosphere be much affected by the velocity of the device at detonation.? What fraction of the blast is caused by the expansion of the stationary surrounding atmosphere due to the radiation.? How long does the actual detonation of the nuclear material take? (as opposed to the lifetime of the resulting fireball)

I'll just phone up the MOD experts and ask them now

Most astronomical circles agree that it must have been a smallish comet. That should probably be added to this entry somewhere...

- X

Ignoring things that will have a small effect such as increasing air pressure with decreasing altitude and gravity, the blast from an air-burst explosion will expand as a sphere in the atmosphere.
Where this expanding sphere hits the ground, I would expect the blast wave to expand along the surface as if this sphere were expanding through the surface. If the surface were not level with the sphere the resulting blast shape would expand outward away from the highest point closest to the epicentre of the blast in an elongated oval shape.
(For golfers - think of the splash shape a golf ball makes as it hits a sand bunker).
All explosions will happen in this way - and the only reason we would have to sauspect this of being a nuclear explosion is that we are only used to super large explosions in a nuclear context....but a meteorite or comet air-burst explosion would easily cause as much blast as any nuclear device and wouldn't leave behind tell-tale radioactive isotopes....which haven't been found.

..as for the rate of expansion of the shockwave - I have in the back of my mind 10 times the speed of sound (3km / second) Does this sound right?

3km/s sounds reasonable to me.

Though personally, I doubt any alien involvement, I suppose in the interests of fairness we should consider that a pure fusion or antimatter explosion might not necessarily leave much isotope trace behind either.

I tend towards the "small, fast ice-comet entering the atmosphere" theory myself, but I also have a sneaking admiration for one of the wackier non-UFO theories I once read in the "Fortean Times"...

Apparently, in the early 1900s, Nikola Tesla was experimenting with means of transmitting power without cables. He had achieved some degrees of success, with fields full of light bulbs on sticks being illuminated by a remote RF power source. In 1908, there was an expedition to the North Pole, and Tesla is on record as saying he would try to "retune" his power transmission device to provide a "spectacular light show" for the brave explorers... The Tunguska explosion took place during this remote power transmission experiment, and Tesla dropped the research... He seemed to think there was a connection, even if no-one else did.

It was a small comet. There is no need for any Ju Ju Flop or Pseudo Science here. It were a lump of rock, some ice and debris.
Vast amounts of released energy do not have to manifest as of nuclear origin.

I do not believe in Little Green Men. They are grey. But I doubt they would fly millions of miles to drop into an unfashionable part of the world.
On the other hand, perhaps it was someones ego that hit the atmosphere.

See http://pages.prodigy.net/onichelson/tunguska.htm for more details than I could remember...

And in my role as chief pedant, I don't think the soviet union or the KGB would have much information on the event. This is because the Soviet Union did not come into being until 1917 (nine years after the explosion) and the KGB was not formed until the 1950s. If there were official records they *may* have survived the revolution, but who knows.
There aren't enough fish in this thread so here's one :

Return tha Babel fish at once you rotter!

Grey Area, I doubt if it was an ego, Elton John was not alive then.

Sorry, had to correct that spelling. ;-0
Actually, I'm surprised that this doesn't happen more often. There is a lot of rock and ice whizzing around out there. It's bound to hit sooner or later, and not just the grain of sand sized stuff. Ah, I've given myself something else to worry about!

Well you could go out and get odds on comet impact, but would you be around to collect your winnings

I agree that there are loads and loads of meteorites and comets out there but both they and we are very small and in the vastness of space this makes the risk of collision less....its just that the effect of the collision is quite major .

the Earth is basicly a target in a cosmic railgun one of these days a huge lump is going to come and hit us and the question we have to ask is do we have a bruce willis in our society?