MIT scientists found the oldest evidence of magnetism in meteorite dust, suggesting magnetic fields helped form the early sun.
Roughly 4.6 billion years ago, our entire solar system was just a giant cloud of gas and dust. Scientists have long assumed gravity alone pulled that cloud into the sun and planets. New MIT research suggests gravity had help.
The team found traces of an ancient magnetic field locked inside some of the oldest known meteorite material. It’s likely the earliest evidence of magnetism ever found from the infant solar system.
Why This Discovery Matters
The transformation from a shapeless cloud of gas into a flat, spinning disk of matter is one of the most important moments in solar system history. That disk eventually condensed into the sun and the planets orbiting it.
“This transition, from a spherical cloud to a protoplanetary disk, is one of the most significant events in all of solar system history,” said Benjamin Weiss, the Robert R. Shrock Professor of Earth and Planetary Sciences at MIT. “It has long been theorized that gravity caused this, but our measurements show magnetism likely played a role.”
The findings appear this week in the Proceedings of the National Academy of Sciences, authored by Weiss along with lead author Cauê Borlina and colleagues from MIT, Tsinghua University, Cambridge University, Caltech, and UCLA.
How a Meteorite Can Preserve a Billion-Year-Old Magnetic Field
Magnetic fields form when electrically charged matter moves around. In the earliest solar system, a collapsing cloud of gas and dust could have generated a plasma of charged particles, and their spinning motion could have created and sustained a magnetic field.
If that happened, tiny magnetic minerals forming inside the disk would have locked in the field’s strength at that exact moment — like a fossil record of magnetism. If a piece of that material survived intact for billions of years, scientists today could measure it directly.
That’s exactly what the team went looking for.
A Remarkably Well-Preserved Meteorite
The researchers analyzed DOM 08006, a meteorite discovered in Antarctica’s Dominion Range in 2008. It’s considered one of the most primitive meteorites ever found, containing mineral grains that date back to the earliest stages of solar system formation — possibly even before the sun itself existed.
What makes DOM 08006 special is how little it’s changed. “Other meteorites went through many different processes over this 4.5 billion year history,” Weiss said. “They were formed in the solar nebula, then added to bodies with water, then got destroyed, moved to the asteroid belt, and then landed here. But somehow, DOM has experienced less alteration than any other meteorite.”
Inside the meteorite, the team isolated tiny mineral grains called calcium-aluminum-rich inclusions, or CAIs — believed to be the oldest solid material in the entire solar system. These particular grains formed within the solar system’s first 200,000 years.
“We know they are the oldest things we have of the early solar system,” said Borlina, who led the study as an MIT graduate student and is now an assistant professor at Purdue University. “But CAIs are very complex and are not all the same, even within a 1-millimeter piece of the meteorite. So we have to carefully identify what types they are.”
A Magnetic Field Stronger Than Earth’s Today
After isolating CAIs containing naturally magnetic minerals like iron, the team ran a series of tests to measure any leftover magnetism. They found it.
Based on their measurements, the researchers estimate the early solar system’s magnetic field measured somewhere between 150 and 600 microteslas — about three to 12 times stronger than Earth’s magnetic field is today.
“We think these kinds of magnetic fields were helping to move gas from the protoplanetary disk, in toward this central star, the sun,” Borlina said. “Gravity is also playing a role. But we are now showing that, if you want to fully understand how the sun and planets formed, you should include magnetic fields in the ingredients that make them.”
Filling in a Long-Standing Gap in the Timeline
The team had previously found evidence of a magnetic field as early as 2 million years into the solar system’s formation, a point when the sun already existed and planets were just starting to form. This new finding pushes that evidence back much further, to a moment before the sun itself had even come together.
“Nowadays people don’t debate whether magnetism is present when planets are forming,” Borlina said. “But the debate is around the very early solar system, before planets are forming, when there’s just a disk. That’s where the debate still resides, and that’s where we’re operating now.”
The research was supported in part by NASA.