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One hundred and eighty!!!

Started by Tank, September 27, 2022, 06:37:46 PM

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Dark Lightning

An infall of sand wouldn't reach the surface, generally speaking. A solid object of the same mass striking the earth would be a catastrophic event, like a dinosaur-killing one.

Tank

Quote from: Bluenose on October 06, 2022, 01:38:30 AM
Quote from: Tank on October 05, 2022, 07:04:07 PMWould you rather be hit by a rock or the equivalent weight of sand? Or put it another way one 1,000kg rock or that rock cut into 100,000 pieces. I would think that one rock would make it to ground but the 100,000 pebble would burn up through the atmosphere.

Well, the amount of kinetic energy to be transferred to the Earth system would be the same. If the solid rock is big enough to be a cause for concern, the same mass of sand would still have major consequences of the same order of magnitude.

The kinetic energy would be the same. But the surface area of the sand and thus drag would be considerably higher. The sand would spread out and burn up high in the atmosphere. Hardly anything would reach the surface if anything at all.

Thousands of tons of dust and small space debris fall on the Earth yearly and we don't even notice most of it.

https://en.wikipedia.org/wiki/Cosmic_dust
If religions were TV channels atheism is turning the TV off.
"Religion is a culture of faith; science is a culture of doubt." ― Richard P. Feynman
'It is said that your life flashes before your eyes just before you die. That is true, it's called Life.' - Terry Pratchett
Remember, your inability to grasp science is not a valid argument against it.

Bluenose

Quote from: Tank on October 06, 2022, 08:21:27 AMThe kinetic energy would be the same. But the surface area of the sand and thus drag would be considerably higher. The sand would spread out and burn up high in the atmosphere. Hardly anything would reach the surface if anything at all.

Thousands of tons of dust and small space debris fall on the Earth yearly and we don't even notice most of it.

https://en.wikipedia.org/wiki/Cosmic_dust

However, the in-fall of dust is spread over the whole atmosphere plus the whole year, so each particle is essentially its own thing.  However, if we are talking about a large lump of sand, IOW an object like the NASA Dart object loosely held together by mutual gravity, then the effect of each grain of sand would not be independent, and the effects would be cumulative since they would not be spread over the whole atmosphere but concentrated in a relatively small area and at the same time.

This has always been my problem with the Hollywood trope of blasting an incoming asteroid with atomic weapons shortly before it hits the Earth.  The best that could actually hope to achieve if to increase the area of devastation.  The real solution to an Earth bound object is the one just tested by NASA, which is to nudge the object during part of its orbit well before it is a danger to the planet.  The amount of delta-V required in that scenario is orders of magnitude less than trying to divert it just before it hits.
+++ Divide by cucumber error: please reinstall universe and reboot.  +++

GNU Terry Pratchett


Tank

The rubble would spread out. Not across the entire planet but a significant area. A solid rock would not.
If religions were TV channels atheism is turning the TV off.
"Religion is a culture of faith; science is a culture of doubt." ― Richard P. Feynman
'It is said that your life flashes before your eyes just before you die. That is true, it's called Life.' - Terry Pratchett
Remember, your inability to grasp science is not a valid argument against it.

billy rubin

it has to be a distant enough nudge to ensure a clean miss. if it just means the asteroid is deflected enough to hit calcutta instead of paris, things will get ugly


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

Tank

I think we are discussing different issues here. One is the nature of asteroids, are they mostly solid or piles of rubble? Another is what happens when a solid or rubble asteroid hits the atmosphere? Another is how to disperse or deflect an asteroid well away from the Earth so it doesn't even impact.



If religions were TV channels atheism is turning the TV off.
"Religion is a culture of faith; science is a culture of doubt." ― Richard P. Feynman
'It is said that your life flashes before your eyes just before you die. That is true, it's called Life.' - Terry Pratchett
Remember, your inability to grasp science is not a valid argument against it.

Bluenose

Quote from: Tank on October 07, 2022, 09:48:56 AMThe rubble would spread out. Not across the entire planet but a significant area. A solid rock would not.

Why would it be spread out?
+++ Divide by cucumber error: please reinstall universe and reboot.  +++

GNU Terry Pratchett


Tank

Quote from: Bluenose on October 07, 2022, 11:59:29 PM
Quote from: Tank on October 07, 2022, 09:48:56 AMThe rubble would spread out. Not across the entire planet but a significant area. A solid rock would not.

Why would it be spread out?

Differential aerodynamic drag.
If religions were TV channels atheism is turning the TV off.
"Religion is a culture of faith; science is a culture of doubt." ― Richard P. Feynman
'It is said that your life flashes before your eyes just before you die. That is true, it's called Life.' - Terry Pratchett
Remember, your inability to grasp science is not a valid argument against it.

billy rubin

when a super nova blows up and heavier stuff like iron is transmuted, what is the next step?

i have some iron meterorites i picked up in the desert in arizona. they are solid chunks of metal.

were iron atomsnjust floating around that magically coalesced into what i habe, or were they smashed into solid chunks during the supernova events?

obviously the asteroids were never part of a preexisting planet, so whether they are solid, or accreted solid, or loose sandballs depends on prior history


"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

Asmodean

My limited understanding is this;

After a supernova, what you are left with is a planetary nebula. Basically, it's a cloud of gas and dust. Gravity acts on it and tiny clumps of stuff clump together to form larger and larger clumps until eventually, they become what passes for meteorites.

As I see it, and this is probably somewhat simplistic, it makes sense for the thing to be iron for two reasons. One is that before impacting the Earth, the thing has to travel through the atmosphere. If it has a coating of "weaker" stuff, that coating burns up as a result of atmospheric friction. The other component is that iron is the last fusion product a star makes, so it is made in a layer of sorts, such that after the supernova event, while iron is dispersed, it's still more likely to find other iron to clump together with than, say, carbon or nickel.

That said, I seem to remember having read that the supernovae are where the heavier elements are produced. It takes more energy to fuse iron than that fusion releases, so iron cannot be used as a star fuel in the conventional sense. However, given such energy, it can be smashed together with stuff in order to make even heavier stuff. The amounts, however, would be rather on the tiny side, and this seems to hold when we look at what the Universe is made of (speaking of matter only, for the purposes of this thread) so it's possible that your meteorites contain trace amounts of this and that, heavier than iron - as well as some lighter elements, should they have survived the trip through the atmosphere still attached to their lump of iron.

Still, it would be interesting to hear a take from someone less pedestrian than me on the subject.
Quote from: Ecurb Noselrub on July 25, 2013, 08:18:52 PM
In Asmo's grey lump,
wrath and dark clouds gather force.
Luxembourg trembles.

Tank

If religions were TV channels atheism is turning the TV off.
"Religion is a culture of faith; science is a culture of doubt." ― Richard P. Feynman
'It is said that your life flashes before your eyes just before you die. That is true, it's called Life.' - Terry Pratchett
Remember, your inability to grasp science is not a valid argument against it.

Bluenose

Quote from: Tank on October 11, 2022, 09:48:15 PMIt worked  ;D

Nasa's Dart spacecraft 'changed path of asteroid'

Yes, indeed!  Regrettably, I wonder just how many of the general public understand that this approach will only work on a threatening object if it is detected early enough to be able to impact it in a part of its orbit where the delta-V required is very small.  An approaching object on a hyperbolic trajectory is an altogether different kettle of fish.
+++ Divide by cucumber error: please reinstall universe and reboot.  +++

GNU Terry Pratchett


Tank

I wonder just how many of the general public understand... anything.  :'(  :'(  :'(
If religions were TV channels atheism is turning the TV off.
"Religion is a culture of faith; science is a culture of doubt." ― Richard P. Feynman
'It is said that your life flashes before your eyes just before you die. That is true, it's called Life.' - Terry Pratchett
Remember, your inability to grasp science is not a valid argument against it.

billy rubin



"I cannot understand the popularity of that kind of music, which is based on repetition. In a civilized society, things don't need to be said more than three times."

Asmodean

Quote from: Tank on October 12, 2022, 08:32:43 AMI wonder just how many of the general public understand... anything.  :'(  :'(  :'(
Yes. Humans bad. General humans worse. >:(

Speaking of detection time, are we not likely to be forewarned about a cataclysmic asteroid impact type of event years and years in advance? But then again, for all I know, those years and years may be years and years too late to sufficiently alter its course with a kinetic impactor... Yeah. There is that.

On a unrelated topic, watched me some PBS Spacetime yesterday, and they were talkuing about ways of mapping extrasolar planets using gravitational lensing around the Sun with fleets of small solar sail ships... Now that would be really cool. I do hope I get to see a actual picture of the surface of a planet orbiting another star - even if it's more barren than the Moon - before I kick the proverbial bucket.
Quote from: Ecurb Noselrub on July 25, 2013, 08:18:52 PM
In Asmo's grey lump,
wrath and dark clouds gather force.
Luxembourg trembles.