Astronomers have reconstructed a fairly complete scenario for planet formation

"Over the past decades, astronomers have reconstructed a fairly complete scenario for planet formation, from minute dust motes clumping together to the emergence of rocky spheres thousands of kilometers across like our Earth, or larger gas giants like Jupiter. Key elements of that scenario are anchored in simulations and measurements, but direct observations (“can’t we just watch how planets form?”) have been notoriously absent."

https://www.mpg.de/26990768/astronomers-produce-the-first-complete-picture-of-gas-planet-formation-in-action