Oldest material on Earth found inside meteorite that hit Australia

Oldest material on Earth found inside meteorite that hit Australia

Oldest material on Earth found inside meteorite that hit Australia

One meteorite that is known to contain presolar grains is the Murchison meteorite, a large, over 100 kilogram (220 pound) chunk of space rock that exploded in the sky over Murchison, Australia in September 1969, scattering its fragments all over the place.

"Only a few meteorites are as large as Murchison and as rich in grains as Murchison", he said.

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

Heck notes that there are lifetimes' worth of questions left to answer about presolar grains and the early Solar System.

Some of those presolar materials-microscopic grains that formed before the sun, measuring about 2 to 30 micrometers across-have been dated at 4.6 to 4.9 billion years old.

"They're solid samples of stars, real stardust", Heck, who led the research published in the scientific journal Proceedings of the National Academy of Sciences, said in a statement.

"We came to the conclusion that about 7 billion years ago there must have been an episode of enhanced star formation, probably about 50 per cent more stars formed than normal". A few were quite old, more than 5.5 billion years old, but majority were younger, between 4.6 and 4.9 billion years old.

This article is based on text provided by the Field Museum of Natural History. The age distribution of the dust - numerous grains were concentrated at particular time intervals - provided clues about the rate of star formation in the Milky Way galaxy, the researchers said, hinting at bursts of stellar births rather than a constant rate. And in a meteorite that fell fifty years ago in Australia, scientists have now discovered stardust that formed 5 to 7 billion years ago-the oldest solid material ever found on Earth.

"But thanks to these grains, we now have direct evidence for a period of enhanced star formation in our galaxy 7 billion years ago with samples from meteorites".

Presolar grains have been discovered in other meteorites before, such as the Hypatia stone and LAP-149, but their ages weren't able to be pinned down. "It's like burning down the haystack to find the needle", says Heck. The new study is evidence of the latter.

Exposure age data allowed the researchers to measure their exposure to cosmic ray.

Alexandrova clinches first WTA Tour title
Ekaterina Alexandrova made it to her second WTA Tour final by beating Garbine Muguruza 6-4, 6-2 on Friday at the Shenzhen Open . With that, the Russian sealed a 6-2, 6-4 win in 73 minutes, and can now enter the Australian Open full of confidence.

Heck said about 70,000 meteorites are now known to science, and of those, "at most 5% of these contain 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".

Isotopes like neon-21 are created when the meteorite was bombarded with galactic cosmic rays.

But the age of the presolar grains wasn't the end of the discovery.

The study authors measured the amount of neon in the grains using an instrument called a mass spectrometer at ETH Zurich, a technology university in Switzerland. The concentration of certain isotopes provides an estimation of how long ago the rock was zapped by the rays.

The scientists analysed how cosmic ray exposure had altered the samples over time.

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.

"Some of these cosmic rays interact with the matter and form new elements". They can exist for billions of years before dying and expelling their key ingredients into space. They're born when bits of dust and gas floating through space find each other and collapse in on each other and heat up.

Most of the grains in the Murchison meteorite came from various stars that formed around the same time.

"And then it took about two to two-and-a-half billion years for those stars to become dust producing", Heck explained.

"The presolar grains are a tiny fraction of meteorites like Murchison, only parts per million", Dr Heck said. With more grains, researchers can refine their age estimates to further test the accuracy of the method.

"It's so exciting to look at the history of our galaxy". "The incredible 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".

Recommended News

We are pleased to provide this opportunity to share information, experiences and observations about what's in the news.
Some of the comments may be reprinted elsewhere in the site or in the newspaper.
Thank you for taking the time to offer your thoughts.