Home Science Space Meteorite Contains Oldest Material on Earth: 7-billion-Year-Old Stardust

Meteorite Contains Oldest Material on Earth: 7-billion-Year-Old Stardust

Stars have life cycles. They’re born when bits of dust and gas floating through space find each other and collapse in on each other and heat up. They burn for millions to billions of years, and then they die. When they die, they pitch the particles that formed in their winds out into space, and those bits of stardust eventually form new stars, along with new planets and moons and meteorites.

And in a meteorite that fell 50 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. Philipp Heck, a curator at the Field Museum, associate professor at the University of Chicago, and lead author of a paper published in PNAS, said:

The materials Heck and his colleagues examined are called presolar grains-minerals formed before the Sun was born. “They’re solid samples of stars, real stardust,” says Heck. These bits of stardust became trapped in meteorites where they remained unchanged for billions of years, making them time capsules of the time before the solar system.

But presolar grains are hard to come by. They’re rare, found only in about 5 percent of meteorites that have fallen to Earth, and they’re tiny — a hundred of the biggest ones would fit on the period at the end of this sentence. But the Field Museum has the largest portion of the Murchison meteorite, a treasure trove of presolar grains that fell in Australia in 1969 and that the people of Murchison, Victoria, made available to science.

Dust-rich outflows of evolved stars similar to the pictured Egg Nebula are plausible sources of the large presolar silicon carbide grains found in meteorites like Murchison. Credit: NASA, W. Sparks (STScI) and R. Sahai (JPL). Inset: SiC grain with ~8 micrometers in its longest dimension. (Image: Janaína N. Ávila)
Dust-rich outflows of evolved stars similar to the pictured Egg Nebula are plausible sources of the large presolar silicon carbide grains found in meteorites like Murchison. Credit: NASA, W. Sparks (STScI) and R. Sahai (JPL). Inset: SiC grain with ~8 micrometers in its longest dimension. (Image: Janaína N. Ávila)

Presolar grains for this study were isolated from the Murchison meteorite for this study about 30 years ago at the University of Chicago. Jennika Greer, a graduate student at the Field Museum and the University of Chicago and co-author of the study, explained:

This “rotten-peanut-butter-meteorite paste” was then dissolved with acid until only the presolar grains remained. “It’s like burning down the haystack to find the needle,” says Heck. Once the presolar grains were isolated, the researchers figured out from what types of stars they came and how old they were. Heck explained:

By measuring how many of these new cosmic ray-produced elements are present in a presolar grain, we can tell how long it was exposed to cosmic rays, which tells us how old it is. The researchers learned that some of the presolar grains in their sample were the oldest ever discovered — based on how many cosmic rays they’d soaked up, most of the grains had to be 4.6 to 4.9 billion years old, and some grains were even older than 5.5 billion years.

Scanning electron micrograph of a dated presolar silicon carbide grain. The grain is ~8 micrometers in its longest dimension. (Image: Janaína N. Ávila)
Scanning electron micrograph of a dated presolar silicon carbide grain. The grain is ~8 micrometers in its longest dimension. (Image: Janaína N. Ávila)

For context, our Sun is 4.6 billion years old, and the Earth is 4.5 billion. But the age of the presolar grains wasn’t the end of the discovery. Since presolar grains are formed when a star dies, they can tell us about the history of stars. And 7 billion years ago, there was apparently a bumper crop of new stars forming — a sort of astral baby boom. Heck said:

This finding is ammo in a debate between scientists about whether or not new stars form at a steady rate, or if there are highs and lows in the number of new stars over time. Heck said:

Heck notes that this isn’t the only unexpected thing his team found. As almost a side note to the main research questions, in examining the way that the minerals in the grains interacted with cosmic rays, the researchers also learned that presolar grains often float through space stuck together in large clusters, “like granola,” says Heck. “No one thought this was possible at that scale.”

Heck and his colleagues look forward to all of these discoveries furthering our knowledge of our galaxy, saying:

Heck notes that there are lifetimes’ worth of questions left to answer about presolar grains and the early Solar System, saying:

Greer added:

Heck said:

Greer concluded, saying:

Provided by: Field Museum [Note: Materials may be edited for content and length.]

Like this article? Subscribe to our weekly email for more!     

Troy Oakes
Troy was born and raised in Australia and has always wanted to know why and how things work, which led him to his love for science. He is a professional photographer and enjoys taking pictures of Australia's beautiful landscapes. He is also a professional storm chaser where he currently lives in Hervey Bay, Australia.

Most Popular

Unconventional Warfare in Arizona: Retired US Army Colonel Describes Election Interference

Ret. Army Colonel Philip Waldron, before a select panel of Arizona legislators and the President's legal team, described U.S. election interference related to Dominion...

Michael Flynn: Communist China Backer of Coup Against the President

Michael Flynn, the retired lieutenant general recently pardoned by Donald Trump from an unproven Russia related criminal case, has warned that the President is...

Cybersecurity Expert Warns Up to 1.2 Million Invalid Votes in Pennsylvania Alone

On Nov. 25, the GOP Pennsylvania Senate Policy Committee held a public hearing to discuss irregularities and other issues surrounding the 2020 elections. Ret....

Sidney Powell Takes Aim at Georgia’s Voting Infrastructure Contracts

Lawyer Sidney Powell has called for an investigation into the Georgia voting contract that was given to Dominion Voting Systems. She has filed lawsuits...