In a stunning revelation that challenges our understanding of the solar system's history, an international team of planetary scientists has discovered evidence suggesting that Jupiter—the largest planet in our solar system—was once approximately 2.4 times larger than its current size.
The findings, published in the prestigious journal Nature Astronomy, indicate that Jupiter likely underwent a dramatic period of mass loss early in its formation, shedding significant portions of its gaseous outer layers while retaining its massive core.
Revolutionary Discovery
"This completely transforms our understanding of gas giant evolution," said Dr. Elena Vasquez, lead author of the study and astrophysicist at the Max Planck Institute for Solar System Research. "We've always known that planets can gain mass through accretion, but the idea that Jupiter could have lost such a significant portion of its mass challenges existing models."
The research team made their discovery by analyzing data from NASA's Juno spacecraft, which has been orbiting Jupiter since 2016. By examining subtle gravitational anomalies and the planet's core composition, they identified isotopic signatures that could only be explained by a much larger original mass.
Cosmic Mystery
The study suggests that approximately 4.5 billion years ago, when our solar system was still forming, Jupiter may have experienced a catastrophic interaction with another massive body—possibly a proto-planet or even a passing star—that stripped away much of its outer hydrogen and helium layers.
"If Jupiter had maintained its original mass, it might have evolved into a brown dwarf—an object intermediate between a planet and a star," explained Dr. James Chen, co-author and planetary scientist at the California Institute of Technology. "This would have dramatically altered the entire architecture of our solar system."
Implications for Exoplanet Research
The discovery has significant implications for our understanding of exoplanetary systems as well. Astronomers have observed many Jupiter-sized planets orbiting close to their stars, but fewer super-Jupiters in the size range that Jupiter may once have been.
"This suggests that mass loss might be a common evolutionary pathway for gas giants across the galaxy," said Dr. Vasquez. "What we're seeing could be the survivors—planets that managed to retain enough mass to remain stable after similar catastrophic events."
The research team plans to extend their analysis to Saturn, Neptune, and Uranus to determine if these planets might also have experienced significant mass loss during their formation.
"We're rewriting the history of our solar system," Dr. Chen concluded. "This discovery opens up entirely new questions about how planetary systems form and evolve over billions of years."