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The Tunguska Event

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Re: The Tunguska Event

#2
I read an entire book about the Tunguska explosion when I was in junior high, but it's interesting that astronomers now think an event like this could happen every 300 years.

Re: The Tunguska Event

#3
The scaling with meteor size is impressive.

A 100 m object will flatten some trees in Siberia.

A 10 000 m object will kill 75% percent of all species on the planet (the KT event).

Re: The Tunguska Event

#4
I'm curious if we could mine in areas where large asteroids impacted and gets lots of minerals. Why do asteroid mining if we already have a few in the ground?

Re: The Tunguska Event

#5
> Given a long enough time period, there is a nearly 100-percent chance an asteroid large enough to destroy most life on Earth will impact our planet.

No worries. Since quantum mechanics dictates that, given enough time, anything can happen, we can also say that given a long enough time period, life will spontaneously reappear.

Re: The Tunguska Event

#6
post #2

I read an entire book about the Tunguska explosion when I was in junior high, but it's interesting that astronomers now think an event like this could happen every 300 years.

One interesting detail I found, I think, on Wikipedia, is that if the meteor had hit about four hours later, due to Earth's rotation, it would have roughly hit Saint Petersburg.

If such events happen so frequently, we're pretty lucky so far. Given that much of Earth is covered in water, I could imagine a lot of these simply hit the ocean, but I don't know what would happen if it hit close to the coast.

Re: The Tunguska Event

#7
post #4

I'm curious if we could mine in areas where large asteroids impacted and gets lots of minerals. Why do asteroid mining if we already have a few in the ground?

I saw a documentary a couple of years back which looked into a correlation of former (likely/suspected) meteor impact sites and natural resources. It looked like lots of areas rich in interesting metals/minerals turned out to probably have been hit by meteors in the past.

So in a way, we are doing that already (at least if that documentary was not totally bogus).

Re: The Tunguska Event

#8
post #6
post #2

I read an entire book about the Tunguska explosion when I was in junior high, but it's interesting that astronomers now think an event like this could happen every 300 years.

One interesting detail I found, I think, on Wikipedia, is that if the meteor had hit about four hours later, due to Earth's rotation, it would have roughly hit Saint Petersburg. If such events happen so frequently, we're pretty lucky so far. Given that much of Earth is covered in water, I could imagine a lot of these simply hit the ocean, but I don't know what would happen if it hit close to the coast.

a simple hit of ocean might be more devastating than hitting uninhabited parts of taiga. think about massive tsunami (at least that's what I would expect, depending on the impact force of course)

Re: The Tunguska Event

#9
post #3

The scaling with meteor size is impressive. A 100 m object will flatten some trees in Siberia. A 10 000 m object will kill 75% percent of all species on the planet (the KT event).

The problem with the latter is that it will cause a nuclear winter. So that 75% will not die instantly but in 2-3 years after the impact. Add an order of magnitude or even half of that and then you have an extinction level event. It could kill organisms even at microbe level.

Re: The Tunguska Event

#10
post #5

> Given a long enough time period, there is a nearly 100-percent chance an asteroid large enough to destroy most life on Earth will impact our planet. No worries. Since quantum mechanics dictates that, given enough time, anything can happen, we can also say that given a long enough time period, life will spontaneously reappear.

A more interesting question is : what kind of delay is worth worrying about?

I mean, for instance it is known that life will remain possible on Earth for about 500 million years, after which the Sun will be too bright. We don't seriously worry about it, since so many things can happen in half a billion years that it does not make much sense to try to plan or predict anything in such a timeframe.

Similarly, I personally don't worry about an impactor of 10 km diameter or so. Such an event is so rare that it's not likely to happen in several million years. To me that's still the kind of timeframe it does not make sense to worry about. I'm sure some people will disagree though.

What is the limit? 10,000 years? 1,000? 100?

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