About 4.6 billion years ago the solar system was just a massive ball of gas and dust. Over the next few million years the solar nebula flattened into a disk, which later condensed into the central Sun and the surrounding planets. Gravity has long been considered the dominant force, but MIT scientists have now found ancient magnetic records in the oldest meteorite samples, suggesting that magnetic fields also played a significant role.
The team examined microscopic grains embedded in the Antarctic meteorite DOM 08006, discovered in 2008. These grains are calcium‑aluminum‑rich inclusions (CAIs) that formed within the first 200 000 years of the solar system, making them the earliest known solar material. By isolating CAIs that contain magnetic minerals such as iron and measuring their remanent magnetization, the researchers detected traces of a magnetic field. Their estimates place the nebular field strength at roughly 150–600 µT, about three to twelve times stronger than today’s Earth field.
Such a field could have been generated by the rotating, charged plasma in the early disk, helping to funnel gas toward the central protostar and influencing the aggregation of the first planetary building blocks. The findings imply that a complete model of Sun and planet formation must include magnetic effects alongside gravity.
The study, led by Benjamin Weiss and colleagues at MIT, appears in the Proceedings of the National Academy of Sciences and was supported in part by NASA.
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