For generations, the cosmic nursery has kept one of its secrets tucked away in swirling clouds of dust: how do minuscule grains—no wider than a speck of smoke—mature into the planet-building blocks of our universe? The dilemma lies in what scientists call the meter-size barrier, a stage where growing dust clumps either spiral inward and vanish into the hungry young star or smash themselves to oblivion in high-speed collisions.
But now, a stellar symphony of minds has aimed this enigma. Over 50 astronomers and chemists, hailing from the world’s top scientific institutions, have come together under the sweeping vision of FAUST—the Fifty AU STudy of the chemistry in the disk/envelope systems of Solar-like protostars.
Using the extraordinary vision of ALMA, the Atacama Large Millimeter/submillimeter Array, they’re peering deep into the hearts of stellar cradles, untangling the chemistry and physics that might just rewrite the origin story of planets.
The universe, it seems, has its method for nurturing the seeds of planets—and it’s more ingenious than we imagined.
NASA’s Curiosity rover spots a bed of Earth-like pebbles
By decoding the chemistry of dense molecular gas wrapped around Solar-like protostars, scientists have unlocked a celestial clue to how rocky planets like Earth come to be. In a cosmic first, researchers have directly spotted millimeter-sized dust grains—ten thousand times bigger than the average speck of space dust—nestled within the windswept walls of a protostellar outflow cavity.
These hefty grains didn’t just drift there. They were whisked away by stellar winds from deep within the hot, dense inner disk and cast outward, away from the gravitational tug that might’ve dragged them back in or shattered them in collisions.
By settling far from the chaos, these dust grains gain precious time and space to do what the early solar system once did: cling together, grow, and evolve into the building blocks of planets.
In a stunning peek into how planets are born, astronomers caught millimeter-sized dust grains clinging to the windy walls of a young star system called L1551 IRS5. These grains are much larger than anyone expected to find so early in planet formation—and they may be the unsung heroes of how rocky planets like Earth begin.
A map of interstellar grains in the Milky Way
What’s exciting? These findings suggest that instead of just spiraling into the star or breaking apart, some dust gets swept up and gently dropped off in calmer zones, where it has more time to grow. It’s like the universe giving tiny particles a head start in the race to become worlds.
As Giovanni Sabatini put it, this isn’t just about new science—it might be a glimpse into how our own Solar System was built. And Claire Chandler added, it opens thrilling questions about just how many different ways planets might form across the galaxy. The stars are whispering secrets, and we’re finally starting to hear them.
Journal Reference:
- G. Sabatini et al, FAUST XXIV. Large dust grains in the protostellar outflow cavity walls of the Class I binary L1551 IRS5, Astronomy & Astrophysics (2025). DOI: 10.1051/0004-6361/202554750
