For the first time, researchers have dated the formation of Jupiter by studying tiny, bead-like spheres found preserved in meteorites.
A study by Japan’s Nagoya University and the Italian National Institute for Astrophysics (INAF) found that the gas giant was most likely born 1.8 million years after the solar system began.
The evidence came from studying chondrules, which are 0.1-2 millimeter-wide “molten rock droplets” found in meteorites that fell to Earth’s surface.
Chondrules have long puzzled scientists. How did these tiny spheres form?
The study’s modeling revealed that the immense gravitational forces of a rapidly forming Jupiter were responsible for creating these molten rock droplets.
The violent start
Roughly 4.5 billion years ago, our solar system was a chaotic nursery.
In this swirling disk of gas and dust, a gaseous giant, Jupiter, was coming into existence.
As Jupiter grew to its massive size, its powerful gravity stirred the pot, disrupting the orbits of countless smaller bodies called planetesimals — similar to the asteroids and comets.
These planetesimals, made of rock, dust, and ice, smashed into each other at incredible speeds. The force of these collisions was so immense that the rocks and dust they contained melted instantly.
The impact vaporized the water in the smaller bodies, creating a steam explosion that shattered the molten silicate into microscopic droplets.
The droplets then cooled and solidified, which were later incorporated into asteroids that eventually broke apart and fell to Earth as meteorites.
“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 Professor Sin-iti Sirono, the co-lead author from Nagoya University.
“Previous 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 added.
Dating planet formation
The new study used computer simulations to model Jupiter’s growth and collisions between rocky and water-rich planetesimals in the early solar system.
The model spontaneously generated realistic chondrules, matching the characteristics and abundance found in meteorite data.
The research found that water within the colliding planetesimals was crucial in forming chondrules.
It also proves that chondrule formation was a direct result of planet formation.
The team could pinpoint Jupiter’s birth by correlating the timing of these simulated collisions with the age of chondrules found in meteorites.
“The model also shows 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,” said Dr. Diego Turrini, co-lead author and senior researcher at INAF.
This research offers a new way to date the formation of other planets.
While Jupiter’s formation explains a major period of chondrule creation, meteorites contain chondrules of various ages.
Scientists can now study chondrules of different ages to trace the birth order of the giant planets in our solar system and possibly in other star systems.
The findings were reported in the journal Scientific Reports.