'Sharing' Planets

Two possible planets in the PDS 70 star system may share a common orbit, which would make them the first known Trojan planets. PDS 70b, in the small solid circle, is a confirmed planet similar to Jupiter, the largest planet in our own solar system. Another object, in the dotted circle, is a cloud of dusty debris that may be forming a new planet, or that may be left over from the birth of a planet that's hidden inside the cloud. The larger circle depicts their orbit around the star, PDS 70. This image was produced by ALMA, an array of radio telescopes in Chile. It shows a giant disk of dust around the star that may be giving birth to even more planets. The system is quite young, so it is still taking shape. 'Trojans' are objects that share the orbit of a larger body, held in place by the gravity of the star and the larger body. Jupiter has 12,000 known Trojan asteroids, split into two clumps, one orbiting 60 degrees ahead of the giant planet, the other 60 degrees behind. Astronomers plan to observe the PDS 70 system again in 2026 or later to confirm that the two objects share a common orbit. [ALMA (ESO/NAOJ/NRAO)/Balsalobre-Ruza et al.]