Scientists have uncovered evidence that a weak but persistent magnetic field may have played a critical role in the formation of gas giants like Jupiter and Neptune. Researchers analyzed tiny grains collected from asteroid Ryugu, which were returned to Earth by Japan’s Hayabusa2 mission. The team found that these ancient particles suggest a nebular magnetic field existed beyond 7 astronomical units (AU), where gas giants formed.
Previous studies confirmed a strong magnetic field in the inner solar system, directing gas and dust toward forming planets like Earth, Venus, and Mars. However, its existence in the outer solar system remained unknown. Using a magnetometer, the researchers “rewound” the magnetic history stored within Ryugu’s grains, revealing that the nebular field was extremely weak – no more than 15 microtesla.
This faint force would have been sufficient to attract gas and dust, contributing to the growth of massive planetary bodies like Jupiter and Saturn. The research team compared their results with other meteorites believed to have formed in the outer solar system, finding that even distant regions were influenced by magnetic forces.
Source: https://dailygalaxy.com/2025/03/4-6-billion-year-old-space-asteroid-dust