Two Baby Planets Caught Forming in a Young Solar System’s Mirror

For the first time, astronomers have directly observed two planets forming simultaneously in the dusty disc of a Sun-like star—not as an artistic impression or a simulation, but as measurable gaps carved into WISPIT 2’s protoplanetary disc. The European Southern Observatory’s (ESO) Very Large Telescope (VLT) and Atacama Large Millimeter/submillimeter Array (ALMA) didn’t just spot a second protoplanet; they mapped its gravitational footprint in the disc’s spiral arms, a structure eerily reminiscent of our own Solar System’s infancy.

The sequence matters: the team had detected the first planet in 2022 using ALMA’s radio observations, but its companion remained a hypothesis until VLT’s SPHERE instrument captured near-infrared signatures of the second body. This isn’t about counting planets—it’s about timing. The disc’s dual spiral arms, one tightly wound and one diffuse, suggest the planets are in a resonant lock, a gravitational dance that could explain how Jupiter and Saturn sculpted the asteroid belt.

What makes WISPIT 2 exceptional isn’t its youth (a mere 1–2 million years old) or its Sun-like mass, but the disc’s architecture. The inner planet’s orbit aligns with a sharp dust ring, while the outer one corresponds to a gap in the gas—precisely the kind of structural hierarchy models predict for systems where planets form in situ, not via migration. That distinction is critical: it tests whether our Solar System’s orderly layout is common or a cosmic fluke.

The scientific significance lies in the transition from inference to measurement.

Protoplanetary discs have been imaged before—HL Tau’s iconic rings come to mind—but WISPIT 2 is the first where two planets are caught in the act of accreting material, their orbits and masses constrained by direct observation. Early interpretations suggest the outer planet is 2–3 times Jupiter’s mass, while the inner one hovers around Saturn’s size, but the real breakthrough is the disc’s gas dynamics.

ALMA’s data shows asymmetric flows where the planets are sweeping up material—exactly what theories predict for the final stages of giant planet formation.

Yet the gaps in our knowledge are just as telling. The team hasn’t yet measured the planets’ atmospheric composition, nor confirmed whether the disc’s spiral arms are driven by the planets or external perturbations. And while the system’s resemblance to a young Solar System is tempting, simulations warn that such structures can arise from flyby stars or disc instabilities—resemblance isn’t proof of outcome.

The next phase is operational: the ESO’s Extremely Large Telescope (ELT), set for first light in 2028, will target WISPIT 2 to resolve the planets’ spectra and track their orbital evolution. If the disc’s gas flows match predictions, it would validate the core accretion model over competing theories. If not, we may need to revisit how—and how quickly—planetary systems stabilize.