The study, published in Physical Review Research, shows that chemical signals preserved in zircon crystals, some of the oldest minerals on the planet, reflecting the rhythm of meteorite impacts triggered as our solar system passed through the galaxy’s dense spiral arms.
Lead researcher Professor Chris Kirkland, from Curtin’s Timescales of Mineral Systems Group in the Frontier Institute for Geoscience Solutions, said the findings provide a striking connection between Earth’s geological record and the large-scale structure of our galaxy.
“Zircon crystals act as time capsules of Earth’s history,” Kirkland said. “When we compared changes in their chemistry with maps of gas in the Milky Way, we found they matched the periods when our solar system journeyed through the galaxy’s spiral arms.”
These regions, crowded with stars and interstellar gas, are thought to disturb icy comets at the edge of the solar system, sending some on collision courses with Earth. The impacts, Kirkland explained, released vast amounts of energy, melting sections of the crust and generating more complex magmas particularly when combined with water-rich environments, like that of Earth’s.
“This research suggests that the solar system’s galactic environment played a key role in shaping the continents and influencing the conditions that made life possible,” he said.
The study opens what Kirkland calls “a new frontier” in science, where geology and astronomy can be directly linked.
“Our results show that Earth’s evolution cannot be seen in isolation,” he said. “Astrophysical processes on the scale of the Milky Way may have left their imprint in the rocks beneath our feet, heralding the beginning of an astro-geological science.”