New research from Curtin University suggests that Earth’s history isn’t just written in rocks—it’s also written in the stars.
A team of scientists has discovered that the evolution of our planet’s crust was influenced not only by forces inside Earth but also by the solar system’s journey through the Milky Way.
The study, soon to be published in Physical Review Research, looked at tiny, tough minerals called zircon crystals.
These crystals, some of the oldest on Earth, act like time capsules. They record chemical changes in Earth’s crust across billions of years.
By comparing those chemical records with astronomical maps of gas in the Milky Way, the researchers noticed something remarkable: the timing of changes in the crystals lined up with the periods when our solar system was passing through the galaxy’s spiral arms.
Spiral arms are crowded regions of space filled with stars, dust, and gas. As the solar system traveled through them, powerful gravitational forces may have disturbed icy comets lingering at the edge of our system.
Some of those comets were then knocked out of orbit and sent crashing toward Earth.
According to lead researcher Professor Chris Kirkland, these cosmic collisions delivered enormous bursts of energy.
“The impacts melted parts of Earth’s surface and created complex magmas,” he explained.
When these impacts interacted with water-rich environments on Earth, they may have sped up the development of the continental crust—the foundation for the land we live on today.
This idea challenges the long-held view that Earth’s crust evolved mainly through internal processes such as volcanism and plate tectonics. Instead, the new findings suggest that our planet’s development was partly shaped by the galaxy itself.
Professor Kirkland described zircon crystals as “a unique archive of Earth’s interaction with the galaxy.”
He believes the results open up an entirely new way of thinking about Earth science. “Our research reveals that Earth’s geological evolution cannot be understood in isolation from the broader galactic environment,” he said.
The study also points to an exciting future for science, where geology and astronomy come together in what might be called “astro-geology.”
By connecting changes in Earth’s crust with the solar system’s path through the Milky Way, researchers are beginning to see how cosmic events may have helped create the conditions that allowed life to thrive.
In short, the continents beneath our feet may not just be the product of volcanoes and tectonic shifts.
They may also be a gift from the galaxy, shaped by ancient cosmic journeys and spectacular impacts that left a lasting mark on our planet.
Source: Curtin University.
