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Around 5 to 7 billion years ago, a dying star sent an explosion of particles hurtling through space. Some of this stardust eventually became part of a meteorite that fell in Murchison, Australia, in 1969. New research confirms that it is now officially recognized as the oldest solid material ever found on Earth.
For the latest study, published in *Proceedings of the National Academy of Sciences* 30 years after the research first began, scientists ground up pieces of the Murchison meteorite to analyze its age. The resulting goo was described as having the scent of 'rotten peanut butter.' This unusual odor comes from the breakdown of abiotic organic molecules in the meteorite, explains lead researcher Philipp R. Heck, a curator at the Field Museum in Chicago, in an interview with Mytour.
To further isolate the stardust grains, which are smaller than a period, Heck used acid to dissolve the rock. The team then measured the neon isotopes formed when cosmic rays hit the stardust. The amount of these isotopes serves as a timeline for how long the stardust has been exposed to cosmic rays, allowing scientists to estimate its age. Heck likens this method to using a bucket to figure out how long it’s been raining based on how much water is inside.
The team discovered that the meteorite held particles dating back over 5.5 billion years, potentially as old as 7 billion years. With Earth having formed around 4.5 billion years ago and the Sun about 4.6 billion years ago, this ancient stardust is believed to have originated during a period of intense stellar activity, a so-called 'astral baby boom,' according to the Field Museum. This burst of star formation created the very matter that forms the world we know today.
When these grains formed, 'most of the stars we see tonight in the sky hadn’t been born yet,' says Heck. 'The bright stars that would have illuminated our galaxy were part of the previous generation of stars, our parent stars. [They] created the elements that eventually fueled and shaped the solar system, Earth, and ultimately, us. These stars produced the material that makes up who we are.'
Although the grains in the Murchison meteorite are the oldest solid material found on Earth, many of Earth's gases are far older. For instance, some of the hydrogen in your body may trace back to the Big Bang, which occurred 13.7 billion years ago.
