Nearly Seven-Billion-Year-Old "Real Stardust" Found, Say Scientists

Oldest material on Earth discovered

Dairy farmers collected the fragments and sold kilograms of the meteorite to museums and universities.

The Murchison meteorite was discovered on September 28, 1969 in Murchison, about 160 kilometres north of Melbourne. Now, a new study has identified the oldest known solid material on the planet that precedes the formation of the Solar System.

A meteorite that crash landed near Melbourne fifty years ago was carrying space dust older than the solar system itself, new research suggests. For comparison, the Sun is 4.6 billion years old and the Earth is 4.5 billion.

A Murchison meteorite on display at the National Museum of Natural History in Washington DC.

This ancient interstellar dust, made of presolar grains (dust grains that predate our sun), was belched into the universe by dying stars during the final stages of their lives.

Nonetheless, the oldest yielded a date of around 7.5 billion years dilapidated.

"Despite having worked on the Murchison meteorite and presolar grains for nearly 20 years, I still am fascinated that we can study the history of our galaxy with a rock", Heck added.

The star dust represented time capsules in front of the solar system. The new study is evidence of the latter.

Scientists analyzed how exposure to cosmic rays had changed the samples over time. By figuring out the number of new cosmic-ray produced elements, researchers were able to measure the duration of exposure and date the presolar grains. Many of them had tales to tell about the meteorite's distinctive aroma. "But rarely there is an interaction, [and] one of those protons can hit an atom in the grain". "The silicon can be split into helium and neon", Heck says. The rays break the grains into fragments.

Just a few of those rays interact with the subject they stumble upon and assemble novel ingredients. They have come up with a method to determine stardust's age.

But presolar grains are hard to come by. The grain is about 8 micrometers on its longest dimension.

This stardust is between between 5 billion and 7 billion years old - older than the sun and our solar system.

Presolar grains are more abundant in what we would call these primitive meteorites, Professor Bland said.

However, other dating techniques, such as comparing the isotope ratios left behind by decaying radioactive materials, can not yet be used to provide an absolute date for these ancient dust grains.

"It starts with crushing fragments of the meteorite down into a powder", explains Jennika Greer, a graduate student at the Field Museum and the University of Chicago and co-author of the study.

These pieces of star dust eventually form new stars, as well as new planets, moons and meteorites. "It's not a straightforward way of measuring isotopic abundance and getting an age directly from that measurement. But still, knowing that [some] of those grains are at least 300 million years older than anything in the solar system is ... confirming that they are indeed the oldest solids in the solar system".

Presolar grains for this study were isolated from the Murchison meteorite about 30 years ago at the University of Chicago.

Stars are born when dust and gas floating in space are found, collapse and heat up. Billions of years later, a chunk of that asteroid crashed into Australia.

A microscopic photograph of a presolar grain. With more grains, researchers can refine their age estimates to further test the accuracy of the method. The researchers aged a explicit assemble (isotope) of the part neon - Ne-21 - to this level the grains.

"It's so exciting to look at the history of our galaxy". "The wonderful thing is we have a rock in our collection that we just take out of the cabinet and learn something about the history of our galaxy".



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