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Re: Coincidence of meteor strike and close asteroid approach at same
time.
Posted:
Feb 20, 2013 4:18 AM
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On 02/19/2013 02:52 PM, Robert Clark wrote:
> On Feb 18, 8:46 am, Bjørn Sørheim<bsoer...@nixspam.online.no> wrote:
>> Here you made a MAJOR error. Your argument is way stronger, my friend.
>> You probably didn't do much probability computations?
>>
>> I just choose to accept your numbers for probability of the two
>> phenomena, as they seem to on the right level.
>> So the probability of these two different phenomena occuring within
>> 24hours is found by multiplying their probability for each separate
>> incident. If the probability for the asteroid occuring is Pa, and the
>> meteor occuring is Pm, then the two on the same day is Pa times Pm. So
>> calculating the probability is like this:
>> 1/30x365x30x365=1/119902500, that is 1 over 100 million!
>> So you have to start the discussion over again
>> with this imensly low probability in mind.
>>
>> CNN posted on Saturday an article where an astronomer from Yale came
>> to a very similar number. Unfortunately she shot her in the foot by
>> saying the two trajectories/orbits were incompatiable. She probably
>> bought that statement from NASA.
>> Personally I think these two are connected, and the probability of
>> them occuring together is as shown imensly low if not the first is
>> producing the latter. So it questions why NASA, at least preliminary,
>> said they were not connected.
>>
>> Bjørn Sørheim
>>
>> On Sun, 17 Feb 2013 07:26:38 -0800 (PST), Robert Clark
>>
>>
>> <rgregorycl...@yahoo.com> wrote:
>>> I really don't like coincidences in science. Reports are asteroids
>>> the size of 2012 DA14 getting this close occur about once in 30
>>> years. And meteors the size of the Russian one enter our atmosphere
>>> about similar frequency. But the problem is their both occurring in
>>> the same 24 hour period. If you imagine the asteroid arriving on a
>>> particular day, the question to ask is what is the probability of the
>>> Russian meteor arriving on that same day? Once in 30 years, and then
>>> 365 days in a year, means the chance of this happening is like 1 in
>>> 10,000. That's disturbingly unlikely.
>>> On the other hand if this really is just coincidence, then it should
>>> be kept in mind that chances this low have been quoted in regards to
>>> large asteroids impacting Earth in our lifetime.
>>
>
> Here's the article by the Yale astronomer:
>
> A meteor and asteroid: 1 in 100 million odds.
> By Meg Urry, Special to CNN
> updated 8:16 PM EST, Mon February 18, 2013
> http://www.cnn.com/2013/02/16/opinion/urry-meteor-asteroid/index.html
>
> She states the two have very different orbits so they should be
> unrelated, but acknowledges that the very low probability of their
> both occurring so close to each other in time is puzzling.
> In view of the very real dangers that would arise IF it is the case
> they are related I think we should investigate some possible ways this
> could occur. What I mean by this is cases where we assume asteroids
> that make close approaches but do not impact, and therefore offer no
> threat, still could have associated fragments that do impact.
> One way is mentioned in the comment section to this NASA blog which
> shows the different orbits of the asteroid and the meteor:
>
> How Do We Know the Russian Meteor and 2012 DA14 Aren't Related?
> Posted on Feb 16, 2013 11:37:14 AM | William Cooke | 25 Comments |
> http://blogs.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1361037562855.html
>
> First though, note there are many ways a fragment could be separated
> from the main asteroid. For instance some asteroids are "rubble
> piles", loosely held together by gravity. In this case collisions
> among the individual fragments could send a fragment away from the
> main asteroid body.
> Another is the obvious way of a collision with another asteroid or
> meteor.
> Still another would be outgassing of volatiles that provides another
> force to separate a fragment from the asteroid.
>
> Then once the fragment is separated from the asteroid, over time,
> since it was given some initial boost away and the asteroid gravity is
> so small, it will travel further and further away from the asteroid,
> though still in the same or close orbit. But the key point is
> depending on the direction the fragment is sent, once the asteroid
> comes around to the Earth or Moon or other planet on a close approach,
> that fragment could be much closer to that large gravitating body than
> the asteroid and therefore be sent on a different orbit.
> Then on subsequent orbits it could impact the gravitating body.
> Indeed it could even be captured by the gravitating body, such as the
> Earth, depending on the speed it is traveling with respect to the
> body. For instance asteroid 2012 DA14 was traveling at 18,641 mph,
> about 8.3 km/s on closest approach. At the distance it passed the
> Earth at 17,000 miles this is greater than escape velocity. But it's
> less than escape velocity at the Earth's surface. So a fragment that
> happened to be closer in to use on that closest approach could have
> been captured.
>
>
> Bob Clark
>
This is what I think: it's too early to conclude or speculate
that meteorites and asteroids now have an increased
chance of impacting earth, on average.
dave
--
dracut:/# lvm vgcfgrestore
File descriptor 9 (/.console_lock) leaked on lvm invocation. Parent PID
993: sh
Please specify a *single* volume group to restore.
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