Tiny fragment of a comet found inside a meteorite

She adds that it belongs to a class of primitive carbonaceous chondrite meteorites that have undergone minimal changes since they formed more than 4.5 billion years ago, likely beyond the orbit of Jupiter.

Asteroids and comets both formed from the disk of gas and dust that once surrounded the young Sun, but they aggregated at different distances from it, which affected their chemical makeup.

It bears some striking similarities to extraterrestrial dust particles that are thought to have originated in comets that formed near the solar system's outer edges.

Meteorites like LaPaz, she notes, are great places to hunt for presolar grains, microscopic pieces of stardust formed by stars that predate the solar system.

By undertaking sophisticated chemical and isotopic analysis of the material, Nittler and his colleagues -- who besides Davidson include Carnegie's Conel Alexander as well as Rhonda Stroud and Bradley De Gregorio of the U.S.

"Because this sample of cometary building block material was swallowed by an asteroid and preserved inside this meteorite, it was protected from the ravages of entering Earth's atmosphere," Nittler explains.

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