Scientists have uncovered the mysterious force that helped assemble the Solar System

Ancient meteorites have preserved traces of a powerful magnetic field that raged at the very beginning of the Solar System's life and may have helped transform a cloud of gas and dust into the Sun and planets. The field was 3 to 12 times stronger than Earth's current magnetic field. The study was published in the journal Proceedings of the National Academy of Sciences.

A protoplanetary disk is a rotating cloud of gas and dust surrounding a young star, from which planets form. The key mystery is how the disk's material loses angular momentum and falls toward the center; magnetic fields are considered one of the main "engines" driving this process. Meteorites, in this sense, are invaluable time capsules that have carried material from the dawn of the Solar System to the present day.

Scientists from the Massachusetts Institute of Technology and their colleagues studied microscopic grains — known as calcium-aluminum-rich inclusions — in the meteorite DOM 08006, found in Antarctica in 2008. These inclusions are among the oldest solid bodies in the Solar System and formed during its first approximately 200,000 years.

The magnetic minerals within them acted as tiny "tape recorders": they preserved remanent magnetization, a frozen "imprint" of the field in which they formed — and this imprint has lasted for billions of years. From it, the scientists determined the strength of the ancient field: 150–600 microtesla.

It is believed that such a field was generated and sustained by electrically charged particles swirling in the protoplanetary disk around the young Sun. Magnetic fields in such disks play a key role: they help material lose angular momentum and fall toward the center, "assembling" the star and planets. Previously, the strength of these fields was estimated mainly through theoretical models, but now direct physical evidence has emerged. This refines our understanding of how planetary systems are born — both our own and others throughout the Universe.