Sun may have devoured a super-Earth planet billions of years ago, study suggests

The sun, that steady furnace at the center of our solar system, may have a violent secret buried deep in its core. New research suggests our star consumed a super-Earth planet billions of years ago—and the evidence of that cosmic cannibalism might still be written in the sun's interior structure, waiting to be read.

Mutlu Yildiz and colleagues at Ege University in Turkey arrived at this conclusion by comparing what we actually observe about the sun with what stellar evolution models predict it should look like. The discrepancies are real and persistent: the sun's convection zone is shallower than expected, its internal sound-speed structure doesn't match predictions, and its surface is mysteriously depleted of lithium. For decades, these anomalies have puzzled solar physicists. Yildiz's team wondered whether a single catastrophic event in the sun's youth might explain all three problems at once.

Their hypothesis centers on a super-Earth—a planet between five and ten times Earth's mass. Such worlds are common throughout the galaxy, orbiting distant stars in abundance. Yet our own solar system lacks one entirely. Using advanced stellar evolution software, the researchers modeled what would happen if the young sun, surrounded by the vast disk of gas and dust from which planets form, had engulfed such a world. The calculations converged on a striking result: a super-Earth of that specific mass range would leave exactly the kind of chemical and structural signature the sun displays today. "We thought planetary engulfment might affect the solar structure but did not expect the calculations to converge on such a specific super-Earth mass range," Yildiz said. "That was one of the most interesting outcomes of the study."

The mechanism itself is plausible. In the solar system's infancy, super-Earths could have formed in the inner solar system, perhaps near Mercury's current orbit. As the protoplanetary disk evolved, these planets would have migrated inward through gravitational interactions, eventually spiraling into the young sun. The collision would have been catastrophic—but not necessarily obliterating. Instead, the planet's material would have mixed into the sun's interior, leaving a chemical imprint that persists even now, four and a half billion years later.

What makes this theory compelling is that it offers a unified explanation for multiple solar mysteries. When a planet falls into a star, it deposits material with a different chemical composition than the star's original makeup. That foreign material would alter the sun's internal structure in measurable ways—changing how heat and energy move through its layers, affecting the speed at which sound waves travel through its depths. The lithium depletion, too, could result from the mixing and heating that planetary engulfment would trigger.

Yet the researchers are careful about their claims. The study is built on computer modeling and unexplained solar features, not direct observation. The team acknowledges that other explanations for the sun's anomalies might exist. Their model also doesn't require the planet to have been completely consumed—partial engulfment could produce similar effects. What the work does establish is that the fingerprints of such an event, if it occurred, should still be detectable within the sun's interior through precise measurements of its structure and composition.

Yildiz and his colleagues believe the next phase of research will involve searching for those fingerprints independently, using solar observations and helioseismic data—the study of vibrations that ripple through the sun. If such evidence can be found, it would rewrite our understanding of the solar system's early history and explain why our planetary neighborhood looks so different from the crowded systems we observe around other stars. For now, the sun keeps its secrets. But the hunt is on.