This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In recent 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 Earth, or larger gas giants like Jupiter. Key elements of that scenario are supported by simulations and measurements, but direct observations ("can't we just watch how planets form?") have been notoriously absent.
Now, a team of astronomers led by Myriam Benisty at the Max Planck Institute for Astronomy has captured a new image of planet formation in action. Taken with the ALMA observatory in Chile, the image shows the interactions between WISPIT 2b, a gas giant with five times the mass of Jupiter, and the surrounding gas of its birthplace. Their two papers are available on the arXiv preprint server.
Planets are born in protoplanetary disks consisting of gas and dust, which occur naturally around newly formed stars. Planets form when dust within those disks clumps together. First, larger pebbles form, then clump further to form planetesimals a few to a hundred kilometers in size.
Those planetesimals join to form rocky, planet-size spheres. In a gas-rich part of the disk, such rocky spheres can collect large amounts of gas and become the cores of gas giants like Jupiter or Saturn. Observational evidence for this scenario has mostly been indirect.
Only within the past decade or so have new facilities given astronomers a more detailed look. In 2014, after the millimeter/submillimeter observatory ALMA became fully operational, it delivered the first images of ring-like structures in protoplanetary disks, thought to be caused by young planets. In 2018, astronomers led by Miriam Keppler, then a doctoral student at MPIA, used the SPHERE instrument at ESO's Very Large Telescope to produce the first confirmed image of a protoplanet inside a protoplanetary disk: PDS 70b, within the disk surrounding the star PDS 70.
At a distance of only about 370 light-years from us, the PDS 70 system is close enough for detailed observations. What the system does not currently provide is a chance to study the interaction between a protoplanet and gas in its immediate surroundings. The planets of PDS 70 seem to have cleared their close neighborhoods of gas rather effectively.
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