Researchers at Cardiff University have uncovered evidence that the earliest continents on some planets in our Milky Way formed long before Earth did. Their estimated ages surpass five billion years, suggesting that landmasses appeared amid planetary lifecycles far earlier than our home world. The findings were reported in a peer review styled column within the Research Notes of the American Astronomical Society, a venue known for concise announcements and data-driven insights that push the boundaries of planetary science.
Through careful observations of nearby sun like stars, scientists found that the first continents could emerge roughly two billion years before Earth began its modern plate tectonics. A prime example cited involves planets orbiting the star HD 4614, which lies about 20 light-years from Earth. The research indicates that continental formation in this system occurred long before Earth touched off tectonic activity, hinting at a world where geologic processes carved large landmasses far earlier in its timeline and potentially reshaped climate and biosphere development in ways we are only beginning to understand.
Two other stellar neighbors receive special attention: the planetary systems around HD 76932 and HD 201891, stars that are similar in size to our Sun and situated at distances of roughly 70 and 110 light-years respectively. Observations suggest that their continents may have formed up to five billion years before the corresponding landmasses on Earth, a striking contrast that underscores how planetary histories can diverge dramatically. This insight comes from a broader survey of 29 stars, which points to the possibility that some exoplanetary biospheres could have evolved with greater maturity than Earth’s had at comparable epochs, perhaps driven by earlier continental stability and longer windows for habitable conditions to persist.
To understand these ideas, it helps to recall how continents arise. Plate tectonics describes the movement of large rock slabs floating atop a partly molten mantle. Heat escaping from a planet’s core prevents widespread solidification of the mantle, enabling the drift of continents over geological time. The heat source is primarily radiogenic energy released by elements such as uranium-238, thorium-232, and potassium-40, which decay and release heat that fuels mantle convection. The result is a dynamic surface where continents can grow and shrink, continents can collide to form supercontinents, and oceans can open and close as the crust reorganizes itself. When continents are present, they influence atmospheric composition, ocean circulation, and climate stability—factors that can decisively affect the trajectory of any emerge life. The emerging picture from these exoplanet studies is that a planet can host complex landmasses far earlier than Earth did, potentially creating longer timescales for biological evolution and ecological diversification that scholars are only beginning to map across the galaxy.
Although vast landmasses did not prove necessary for life to originate, Earth’s own history reveals that terrestrial continents contributed importantly to the long-term flourishing of many organisms. If exoplanets already boasted ancient continents, their biospheres could have enjoyed similar or even enhanced opportunities for stability, nutrient cycling, and ecological complexity. In other words, the presence of early land could correlate with advanced life pathways, opening new questions about how universal the conditions for life truly are. The study thus invites a broader dialogue about how continents shape habitability across different planetary environments and how common such ancient geologic features might be in neighboring star systems. These reflections add a compelling dimension to the ongoing search for extraterrestrial life, underscoring that our own planet is one example within a much larger and varied cosmic tapestry.
Experts conclude that these discoveries illuminate why certain planetary systems might stand out as promising targets in the search for life beyond Earth. The interplay between continental development, tectonic timing, and atmospheric evolution forms a fertile ground for future missions and observations that could refine our understanding of where life could take hold and endure across the galaxy.