For the first time, scientists have captured the earliest known stage of rocky planet formation around a star beyond our Sun. Using observations from the James Webb Space Telescope (JWST) and the Atacama Large Millimeter/submillimeter Array (ALMA), researchers detected the initial condensation of solid mineral grains within the disk of a young protostar, marking the birth of a new solar system.
The discovery centers on HOPS-315, a young star located about 1,300 light-years from Earth. It provides a rare glimpse into the birth of a planetary system, offering insights into conditions that likely mirrored those in the early history of our own Solar System.
“For the first time, we have identified the earliest moment when planet formation is initiated around a star other than our Sun,” said Melissa McClure, a professor at Leiden University in the Netherlands and lead author of the study published in Nature.
Solid grains mark first step in planet and new solar system formation
The team detected signs of tiny solid mineral grains beginning to form—alongside silicon monoxide gas—within the protoplanetary disc surrounding HOPS-315. These discs, composed of gas and dust, are the raw materials from which planets eventually emerge. While scientists have previously observed massive, young planets within such discs, spotting the earliest solid ingredients—known as planetesimals—had remained elusive until now.
“We’re seeing a system that looks like what our Solar System looked like when it was just beginning to form,” said co-author Merel van ‘t Hoff, a professor at Purdue University. It’s like looking at a baby picture of our own planetary neighborhood.
Meteorites link Earth’s past to distant star systems
In our Solar System, the first solid materials formed near what is now Earth’s orbit and are preserved in ancient meteorites. These meteorites are rich in silicon monoxide crystals, which only form at high temperatures—conditions found in early planetary discs.
Over time, these tiny grains bonded together, growing in size through collisions until they became mile-sized chunks called planetesimals, the building blocks of planets like Earth and the cores of gas giants such as Jupiter.
Observatories pinpoint how new solar systems emerge
To locate where the new solids were forming around HOPS-315, the team combined the JWST’s infrared sensitivity with ALMA’s precision mapping. The instruments revealed that the silicon monoxide gas—formed in very hot conditions—was starting to turn into solid grains in a part of the disc about as far from the star as the asteroid belt is from our Sun.
Zooming into HOPS-315. For the first time, astronomers witness the dawn of a new solar system. pic.twitter.com/zobIqtHGno
— Black Hole (@konstructivizm) July 17, 2025
“We’re really seeing these minerals at the same location in this extrasolar system as where we see them in asteroids in the Solar System,” said Logan Francis, a postdoctoral researcher at Leiden University.
A rare glimpse into the galaxy’s planetary origins
Edwin Bergin, a professor at the University of Michigan and co-author of the study, emphasized the uniqueness of the finding. “This process has never been seen before in a protoplanetary disc—or anywhere outside our Solar System.”
The discovery not only strengthens the link between extrasolar systems and our own but also highlights the combined power of JWST and ALMA. “I was really impressed by this study, which reveals a very early stage of planet formation,” said Elizabeth Humphreys, an astronomer at the European Southern Observatory who was not involved in the research.
With HOPS-315 offering such a close match to the early Sun, astronomers now have a powerful new model to study how planets begin to emerge from dust and gas, both near and far.
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