WASHINGTON ¨C Scientists have identified Earth¡¯s oldest-known impact crater, and in doing so may have solved a mystery about how our planet emerged from one of its most dire periods.
Researchers have determined that the 45-mile-wide (70-km) Yarrabubba crater in Australia formed when an asteroid struck Earth just over 2.2 billion years ago. The collision occurred at a time when the planet was believed to have been encased in ice and the impact may have driven climate warming that led to a global thaw.
¡°Looking at our planet from space, it would have looked very different,¡± said isotope geology professor Chris Kirkland of Curtin University in Australia, one of the researchers in the study published in the journal Nature Communications. ¡°You would see a white ball, not our familiar blue marble.¡±
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