Recent studies of asteroid Ryugu, visited by Japan's Hayabusa-2 mission, suggest that magnetic fields played a significant role in the formation of celestial bodies in the outer Solar System. Analyzing samples collected from Ryugu, researchers found evidence of a magnetic field during its formation, estimated at around 15 microteslas. This measurement is less than a third of Earth's current magnetic field and significantly weaker than the protoplanetary nebula's field that formed the inner planets, which could have reached up to 200 microteslas.
Despite its relative weakness, the magnetic field was likely sufficient to influence the formation of bodies at distances over seven times that of Earth to the Sun, including the gas giants Jupiter, Saturn, Uranus, and Neptune, as well as numerous comets and asteroids.
Benjamin Weiss, co-author and professor at MIT, emphasized the universal presence of magnetic fields in the early Solar System, stating, 'This applies now to the planets in the outer Solar System.' The Sun formed from a collapsing interstellar gas cloud, which, after its formation, resulted in a rotating protoplanetary disk filled with ionized gas interacting magnetically with the newborn star.
The study, published in AGU Advances, also examined meteorites believed to originate from the distant Solar System, confirming weaker magnetic field measurements consistent with an upper limit of 15 microteslas. The research team is looking forward to analyzing the magnetic field from asteroid Bennu, where NASA's OSIRIS-REx mission has collected samples.