Scientists have unearthed the oldest meteorites ever found on our planet

Geologists and atmospheric scientists have just unearthed the oldest meteorites ever found on our planet. They're 2.7 billion years old and paint a striking picture of Earth's atmospheric history. Oddly, they reveal hints that Earth had an oxygen-rich atmosphere at a time many scientists still agree the planet was still nearly devoid of oxygen.
The 60 meteorites were fossilized in limestone in Western Australia's Pilbara region and unearthed in 2014 and 2015. Each are dust-sized grains, individually smaller than a crosscut of your hair. They were discovered and analyzed by a research team led by Andrew Tomkins, a geologist at Monash University in Melbourne, Australia. As Tomkins reports in a paper published today in the journal Nature, the chemical composition of these meteorites provide the first direct evidence of any kind of the makeup of ancient Earth's upper atmosphere.

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