Scientists have found a comet in an unexpected place: deep in a meteorite, it says in a new article.
The researchers reported finding a 0.1-millimeter carbon-rich rock fragment in a meteorite. They interpreted it as a comet piece that was trapped in the earliest ages of the solar system, when the planets were still forming, and later brought to earth. We simply do not have many comet samples here on Earth, which makes this potential discovery very exciting.
The fragment "may be characteristic of comet material that is not present in meteorite collections because it is too fragile to survive entry into the atmosphere," states the publication published today in Nature Astronomy.
Let's first define a few things: A meteorite is a rock from outer space that has landed on the surface of the earth. It could be part of an asteroid, rocky bodies that were thought to be derived from residuals in the solar system that have not formed into planets or comets that resemble asteroids but contain volatile elements that heat up into an atmosphere (called a coma) and a tail under the influence of the sun. These are clunky terms, but they understand what astronomers are generally interested in – how the solar system came about and how the various objects we see today can retell that story.
The researchers analyzed an Antarctic meteorite called LAP 02342, which is interesting because it was only minimally weathered or eroded during its time on Earth. They analyzed them with an electron microscope, revealing the tiny carbon-rich area that was different from the rest of the otherwise typical meteorite. Its composition was consistent with other interplanetary dust particles that astronomers had previously argued had come from comets.
Humans were not near this meteor form, so we can not determine the exact origin of the fragment. But the researchers have some ideas. Perhaps it was the first stage of a comet that formed the icy cuiper belt from the outermost part of the solar system. But the formation of the comet was somehow stopped, and this piece was grabbed by an asteroid that moved inward towards the sun and finally hit the earth.
Hopefully, scientists will soon find more carbon stains in asteroids to tell the story of the solar system's origins. According to the paper, searchers for carbon-rich pieces in ancient meteorites may "prove valuable in expanding our understanding of the entire spectrum of primitive astronomical materials in the early solar system."