SYDNEY: A meteorite discovered in Canada may be older than the Solar System, according to a new U.S. study.
Samples taken from the Tagish Lake meteorite, discovered in 2000, have revealed evidence of organic matter that predates our Sun and Solar System, according to the study, published in today's edition of the U.S. journal Science.
According to the researchers, the meteorite most likely originated at the outer regions of the Kuiper Belt or in the cold molecular cloud that gave birth to the Solar System.
When analysing the meteorite, the team, led by Keiko Nakamura-Messenger, of the NASA/Johnson Space Center in Texas, discovered "globules" inside it consisting of simple organic compounds with carbon-rich outer layers.
They found that the globules mainly consisted of aliphatic hydrocarbons - hydrogen and nitrogen atoms connected to chains of carbon atoms.
Almost all matter in the Solar System has the same ratio of isotopes of each element, (isotopes are versions of an element with different numbers of neutrons). Isotopic ratios are often exploited by scientists to learn more about the origin of a sample of interest. For instance, the known ratio of carbon-14 to carbon-13 and carbon-12 allows radiocarbon dating provide accurate ages of ancient objects.
Surprisingly, the meteorite globules revealed unusually high ratios of isotopes when compared to the remainder of the meteorite material.
"We recognised the globules that were not from the Solar System from their exotic isotopic compositions," said Nakamura-Messenger.
The isotopic ratios showed that the globules formed at temperatures of about minus 260°C - close to absolute zero. According to Nakamura-Messenger, this means that "the organic globules most likely originated in the cold molecular cloud that gave birth to our Solar System, or at the outermost reaches of the early Solar System."
The meteorite was classified as a "carbonaceous chondrite type" which contain up to 5 per cent by weight organic matter. Notably, it recorded the highest content of carbon in this type of meteorite to date.
Based on the meteorite's initial speed and entry direction, the team calculated its orbit around our Sun, and found that it originated somewhere in the asteroid belt, between the orbits of Mars and Jupiter.
"We can't reach the outer Solar System now by ourselves, but we are able to research the material from there through meteorites. I think this is really cool," said Nakamura-Messenger. "By using our new instruments … we may be one step closer to knowing where our ancestors came from."
