For the First Time Ever We Can See Planets Starting to Form Around a Star

A young star 1,300 light-years away has given astronomers something they have dreamed about for decades: a freeze-frame of the very first step in turning space dust into rocky worlds. Using the James Webb Space Telescope and the Atacama Large Millimeter/submillimeter Array, an international team spotted raw minerals hardening out of vapor inside the disk of gas and dust that circles the infant star HOPS-315 in Orion.

A Baby Star Is Giving Us a Front Row Seat to the Birth of Planets

HOPS-315 is still shrouded in the cloud that birthed it, yet from our angle one wall of that cloud acts like a natural periscope, letting telescopes peer straight into the inner few astronomical units of the swirling disk. In that zone, temperatures soar past 1,300 degrees Kelvin (roughly 1,900 degrees Fahrenheit), hot enough to vaporize rocky dust.

Webb’s infrared spectrographs revealed a strong fingerprint of silicon monoxide gas, the smoking gun for vaporized silicate dust. Right alongside that vapor sat crisp absorption features from newly-forged crystalline grains of forsterite and enstatite, the same magnesium-rich minerals locked inside the oldest meteorites in 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,” says Melissa McClure, a professor at Leiden University in the Netherlands and lead author of the new study, published in Nature.

Why does that pairing matter? Dust in typical protoplanetary disks starts out amorphous — glass-like, not crystalline. To crystallize, the grains must either anneal at moderate heat for a long stretch or, as seems to be happening here, melt completely and then cool. The second route flips the chemical clock back to zero; everything that forms after that point tells the story of a brand-new planetary system. The Webb data show both the melt and the first glitter of solid rock.

Pinning down where the action unfolds called for ALMA’s radio vision. The array mapped millimeter-wavelength emission from silicon monoxide. Those maps showed no sign of the gas in HOPS-315’s high-speed jet — a narrow outflow that rockets away from the star. Instead, the signal hugged a tight ring no wider than the orbit of Mars. In other words, the rock vapor rides inside the disk itself, exactly where planets begin to coalesce.

Merel van ’t Hoff, co-author at Purdue University, calls the result “a baby photo of our own Solar System” saying that “we’re seeing a system that looks like what our Solar System looked like when it was just beginning to form.”

She notes that the minerals appear at roughly the same orbital distance as today’s asteroid belt. That match strengthens the idea that the dusty interior of HOPS-315 mirrors conditions in the nebula that birthed Earth.

In their report, the team states that a “thermostat” region sits near one astronomical unit inside the disk. Material spirals inward, crosses the rock-vapor line, turns to gas, then drifts upward and cools. As it cools, minerals condense layer by layer. Turbulence stirs the mix, lofting some grains high enough for telescopes to detect them against hotter background layers. Computer models predicted such a zone; Webb just provided the first observational proof.

The mineral mix itself tells a deeper story. Forsterite appears in plenty of disks, but the hefty share of enstatite — and a hint of pure silica — suggests that part of the vapor lost magnesium early on, likely because some grains clumped fast and dropped out of circulation. That clumping is the first rung on the ladder from dust to asteroids to planets.

ALMA added another clue: the star’s jet shows far less silicon than expected compared with carbon monoxide. If silicon is missing from the gas, it must already be locked into solids that never reach the jet launch point. Nature seems to be keeping the rock-forming ingredients close to the star, right where future worlds need them.

Elizabeth Humphreys, European ALMA Programme Manager, who was not part of the project, praised the joint-telescope approach.

“I was really impressed by this study, which reveals a very early stage of planet formation. It suggests that HOPS-315 can be used to understand how our own Solar System formed. This result highlights the combined strength of JWST and ALMA for exploring protoplanetary discs.”

What comes next? The researchers aim to revisit HOPS-315 to see whether the fresh crystals grow, drift outward, or fall inward. They are also combing Webb’s archive for similar systems seen from similarly lucky angles. Each new catch will sharpen the emerging picture of how common—or rare—Earth-like worlds may be across the galaxy.

For now, HOPS-315 offers a front-row seat to a process once hidden in meteorites and models. The star may be only a few hundred thousand years old, yet its disk already contains possible future planets. For stargazers on Earth, that makes Orion’s newest spark one of the most intriguing laboratories in the sky.

The findings appeared in the journal Nature.