Meteorite grains divulge Earth's cosmic roots (stars, solar)

[Brian.Pearson]

We had at one point discussed the possibility of meteorites coming from extrasolar sources. I just now came across another article which explains why it must not come from our solar system:

Heck and his colleagues examined 22 interstellar grains from the Murchison meteorite for their analysis. Dying sun-like stars flung the Murchison grains into space more than 4.5 billion years ago, before the birth of the solar system. Scientists know the grains formed outside the solar system because of their exotic composition. "The concentration of neon, produced during cosmic-ray irradiation, allows us to determine the time a grain has spent in interstellar space," Heck said.