Meteorites discovered on Earth escaped the violent formation of the planet Jupiter, and now researchers say these space rocks help date the formation of the largest planet in our solar system to 4.6 billion years ago.
An international team from Japan’s Nagoya University and Italy’s National Institute for Astrophysics (INAF) dated Jupiter’s formation by analyzing molten droplets known as chondrules within meteorites. These droplets, forged from colliding planetesimals—rocky and icy bodies that formed in the early solar system—provide the clearest evidence yet that Jupiter took shape during this turbulent period.
Understanding Chondrules
Chondrules, typically measuring between 0.1 and 2 millimeters in diameter, are found in meteorites originating from ancient asteroids. Their round shapes and origins have remained a scientific puzzle for decades.
In the Nagoya University team’s new work, many details about these meteorites are revealed, including how the planetesimals’ water content led to the droplets’ final size and cooling rate.
“When planetesimals collided with each other, water instantly vaporized into expanding steam. This acted like tiny explosions and broke apart the molten silicate rock into the tiny droplets we see in meteorites today,” said co-lead author Professor Sin-iti Sirono of Nagoya University’s Graduate School of Earth and Environmental Sciences.
Modeling Jupiter’s Formation
“Previous formation theories couldn’t explain chondrule characteristics without requiring very specific conditions, while this model requires conditions that naturally occurred in the early solar system when Jupiter was born,” Sirono said.
By running detailed computer simulations, the researchers tracked Jupiter’s rapid growth. As the planet gained mass, its gravity disrupted nearby planetesimals, causing them to collide violently. The resulting chondrules matched those in meteorite samples in both abundance and appearance.
“We compared the characteristics and abundance of simulated chondrules to meteorite data and found that the model spontaneously generated realistic chondrules,” said co-lead author Dr. Diego Turrini, of the Italian National Institute for Astrophysics.
According to Turrini, the model reveals that “chondrule production coincides with Jupiter’s intense accumulation of nebular gas to reach its massive size.”
“As meteorite data tell us that peak chondrule formation took place 1.8 million years after the solar system began, this is also the time at which Jupiter was born,” he added.
Dating Planet Formation
Going beyond just Jupiter, the findings shed new light on the formation processes behind the solar system itself, although many mysteries still remain. Chondrule-containing meteorites span a wide range of ages, suggesting that other giant planets, including Saturn, may also have contributed to their formation.
The researchers hope to extend their methods to meteorites linked to different planetary eras. Doing so could reveal the order in which the solar system’s planets emerged and help astronomers compare Jupiter’s violent birth with the processes shaping planets in distant star systems.
The paper, “Chondrule Formation by Collisions of Planetesimals Containing Volatiles Triggered by Jupiter’s Formation,” appeared in Scientific Reports on August 25, 2025.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.