Tunguska: Aliens Did It!

[Tuckerfan]

Scientist claims UFO collided with Tunguska meteorite to save Earth.

A Russian scientist claims that aliens downed the Tunguska meteorite 101 years ago to protect our planet from devastation. Yuri Lavbin says he found unusual quartz crystals at the site of the massive Siberian explosion. Ten crystals have holes in them, placed so the stones can be united in a chain, and other have drawings on them. “We don’t have any technologies that can print such kind of drawings on crystals,” said Lavbin. “We also found ferrum silicate that can not be produced anywhere, except in space.”

Actually, I have it on good authority (from someone I can only identify as "Info"), that what really happened was that a starship from Earth's future (we'll call the ship "The Big E") had travelled to the past to rescue a bunch of passenger pigeons and bring them forward to the future, in order that they might communicate with a giant space probe that was menacing the Earth. Unfortunately, someone onboard The Big E, that "Info" will only identify as "the man with the pointy ears," dropped a decimal while doing the necessary calculations and instead of slingshotting them around the sun and back to the future, caused the ship to blow up in the Earth's atmosphere, just above Tunguska.

The quartz crystals are actually made of a material called "dilithium" and were used as part of the engines of The Big E.

[AllWalker]

But the meteorite had material that can only come from space! What, are you telling me the meteorite just happened to pass through space on it's way to Earth? Despite the fact we found it on the ground?

Rocks are heavy. When was the last time you threw a rock and it went into space? Huh?

Yeah. Thought so.

[Elyanna]

I've heard it was anti-matter.

[puppygod]

Ok, it's time to come clean.

I did it.

Sorry. Never gonna happen again. I'll be more careful with my firecrackers next time.

[maggenpye]

Was the pointy eared dude carrying a cherry red blob around with him?

Or was V'ger missing a couple of fuses - again?

I swear, building a space program using only the lowest bidding technology providers was always going to bite ass.

[ivan astikov]

What I always wondered about Tunguska was what happened to the meteorite? How come there is no crater or physical evidence of whatever caused all that damage? Can a meteorite hit earth without leaving a crater? Could a meteorite have actually entered the Earth's atmosphere on such an angle and at such a velocity, that the meteorite "skimmed" the Earth's surface and carried on straight out of our atmosphere again?

[Q.E.D.]

What I always wondered about Tunguska was what happened to the meteorite? How come there is no crater or physical evidence of whatever caused all that damage? Can a meteorite hit earth without leaving a crater? Could a meteorite have actually entered the Earth's atmosphere on such an angle and at such a velocity, that the meteorite "skimmed" the Earth's surface and carried on straight out of our atmosphere again?

It was an airburst a couple miles above the surface. Chances are it was a large rocky meteoroid which couldn't handle the immense pressure once it entered the lower atmosphere and it exploded. It was the shockwave created by this explosion which continued forward and did all the ground damage. Tiny fragments of what is thought to have been the culprit asteroid have been found scattered throughout the site. See .

[ivan astikov]

It was an airburst a couple miles above the surface. Chances are it was a large rocky meteoroid which couldn't handle the immense pressure once it entered the lower atmosphere and it exploded. It was the shockwave created by this explosion which continued forward and did all the ground damage. Tiny fragments of what is thought to have been the culprit asteroid have been found scattered throughout the site.

When has this kind of incident happened before, for scientists to have a comparison?

See .

No offense, but that video was about as helpful as providing a Jackson Pollock painting as a map of China!

[Q.E.D.]

When has this kind of incident happened before, for scientists to have a comparison?

Hiroshima.

And if you mean rocky meteoroids exploding in the atmosphere, it happens all the time.

[ivan astikov]

[quote=Q.E.D.]

When has this kind of incident happened before, for scientists to have a comparison?

Hiroshima.

And if you mean rocky meteoroids exploding in the atmosphere, it happens all the time.[/quote:th2xu3o4]

So how big do they have to be to reach the ground in a large enough lump to make some sort of impact crater?

[Q.E.D.]

It's not so much the size--although that's a factor--as it's the material. Rocky or stony meteoroids are, well, rocky and therefore not terribly strong. There are enormous stresses on a large object passing through the atmosphere at hypersonic velocities and these usually prove too much for rocky material to bear and they explode. Iron meteoroids are much stronger and if they're large enough to survive the compressive heating of atmospheric entry and not burn up, they'll probably make it all the way to the ground. The one which carved out Meteor Crater in Arizona, US, was of this type and to this day, chunks of iron from the impacting body can be dug out of the crater and the surrounding area. Of course, a very large rock will survive just by sheer mass alone.

A Tunguska-sized event is expected to occur about once every 300 years, on average.

[ivan astikov]

What explanation is there for why the majority of impact craters here or on the moon are round, instead of teardrop shaped?

[Q.E.D.]

All craters are round, unless the impact occurs at a very shallow angle. The reason for this is because impacts don't create craters by simply gouging out the ground, they create them by exploding. The force of impact is so high that it compresses both the infalling object and the ground it hits to the point of incandescence--the material gets so hot that it literally vaporizes. This heating and vaporization occurs nearly instantaneously, resulting in a violent shockwave: an explosion. Since the shockwave is spherical, the resultant crater is round.

[ivan astikov]

But some meteorites reach Earth without vaporising, so what's happening there then? If you were to train a telescope on the moon's craters, would you find any of them with large remnants of what hit it?

[Q.E.D.]

Yes, they reach the Earth (or the Moon) without vaporizing in the atmosphere, but one they hit the ground the energy of impact is essentially converted to heat and the whole thing vaporizes instantly in a gigantic explosion.

As for remnants, if it's large enough to blast out a crater then very little of what one might call "large" will be left.

[Baldwin]

In 1178, five monks at Canterbury described witnessing what may have been a large impact on the Moon.

[ivan astikov]

Yes, they reach the Earth (or the Moon) without vaporizing in the atmosphere, but one they hit the ground the energy of impact is essentially converted to heat and the whole thing vaporizes instantly in a gigantic explosion.

As for remnants, if it's large enough to blast out a crater then very little of what one might call "large" will be left.

So how are teardrop-shaped craters made, if it's the resulting shockwave that makes the crater and not the meteor gouging a hole in the earth?

[Q.E.D.]

As I said earlier:

All craters are round, unless the impact occurs at a very shallow angle.

[ivan astikov]

[quote=Q.E.D.]As I said earlier:

All craters are round, unless the impact occurs at a very shallow angle.

[/quote:3vpx8zq5]

Ah, silly me.

So does any of that preclude the possibilty of a meteor coming in at a sufficient angle to not even impact and "whizz right by"?

Any idea of the average speed of an impacting meteor?

How much of a difference would the lack of an atmosphere on the moon have made on a meteors impact?

[Baldwin]

[quote=ivan astikov][quote="Q.E.D.":2pv8ngs5]As I said earlier:

All craters are round, unless the impact occurs at a very shallow angle.

[/quote:2pv8ngs5]

Ah, silly me.

So does any of that preclude the possibilty of a meteor coming in at a sufficient angle to not even impact and "whizz right by"?[/quote:2pv8ngs5]Happens fairly often.

Any idea of the average speed of an impacting meteor?

There are a lot of variables. The Earth is orbiting the Sun at about 60,000 mph. During the Perseid meteor showers in August, we're basically plowing through a trail of cometary debris; so the bits are hitting the atmosphere pretty durn fast.

The vast majority of objects that hit the Earth's atmosphere burn up before ever reaching the ground. Now, if a meteorite is large enough to have a solid piece make impact, but below a certain mass -- say, a brick-sized iron meteorite -- then it may only be going a few hundred miles an hour by the time it gets through 100 miles of atmosphere and hits the ground. Won't explode and make a big crater; and in fact may be cold to the touch.

How much of a difference would the lack of an atmosphere on the moon have made on a meteors impact?

Nothing to slow the object down before impact. Everything hits, from dust-sized particles (a constant rain of micrometeorites) on up.

[Q.E.D.]

Any idea of the average speed of an impacting meteor?

Since Baldwin already gave you the answer to the question you asked, I'll give you the answer to the question I think you meant to ask: The average speed of an incoming meteoroid is around 20 miles per second before it hits atmosphere and can be as high as 50 mi/s. For comparison, a high-powered rifle bullet travels at less than one mile per second.