Hi Mark and all,
As Norbert pointed out, only small microscopic inclusions have been
found that probably contain extra solar material. No specimen that we
have ever found is uniquely from another solar system. There are a
number of reasons for this. First any material would have to travel
great distances (light years) to enter our system. After entering our
system, Earth would have to be lucky enough to be the target of such
material plus material would have to be recovered after the fall. This
puts the odds at great disadvantage. Coming from outside of our solar
system the material would have a far greater speed than any asteroidal
material or planetary material from inside our system, making the chance
of survival less likely. Just like meteoroids that catch up to the
Earth's orbit more often survive passage than meteoroids that have a
head on collision with Earth survive less often due to forces of going
through the atmosphere. We do see these high speed extra solar particals
coming in at speeds many times the speeds of our systems material.
Such extra solar material would have most likely a far greater age. Over
4.6 billion. Such a meteorite would have the age of it's solar system
plus the age of it's travel time to our solar system. The farther away
the material came from the greater the age if you figure out the great
distances between other stars. The farther away the material came from
the less likely it would end up in our system as it should encounter
other systems on the way here.
Each meteorite in our system tends to contain some of the chemical
signature from our Sun which makes it identifiable with our system. An
extra solar meteorite would contain a different chemical signature based
on the abundance of material that comes from that system. Just as no two
stars in the sky contain the same exact spectral make up, no two systems
would contain the same solar signature making it possible to distinguish
such foreign matter to our system. No doubt isotopes would show a much
older age and perhaps even unique types of isotopes that would puzzle
our scientists. Maybe a fourth or fifth type of oxygen isotope that we
use to distinguish Earth/moon system from Vestoids and Martian samples
we have.
Will have to re-read McSween and find out what he had to say about this
and I am sure he did make some comments.
Best!
--AL Mitterling
Mark Crawford wrote:
I'm reading Paul Davies' "The Fifth Miracle". In chapter 6 it refers
to the 1996 discovery by Taylor, Baggaley and Steel of inter-stellar
dust particles entering the earth's atmosphere in the form of fast (>
70-km/s) meteors:
http://www.nature.com/nature/journal/v380/n6572/abs/380323a0.html
It got me wondering as to whether there are any candidates for
meteorites which may be of extra-solar origin. Are there any? How
would they be identified - a suspiciously long CRE age would perhaps
be one indicator?
Mark
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