Magnetic Fields Frozen in Meteorites Reveal Insights into the Birth of Our Solar System

Scientists may have learned a bit more about the birth of our solar system. By examining magnetic fields trapped in grains within a primitive meteorite, researchers have pieced together how the early solar system evolved.

"The measurements made by Fu and Weiss are astounding an unprecedented," said Steve Desch, co-author of the new paper, in a news release. "Not only have they measured tiny magnetic fields thousands of times weaker than a compass feels, they have mapped the magnetic fields' variation recorded by the meteorite, millimeter by millimeter."

When the solar system first formed, it left lots of "construction debris" behind in the form of meteorites. The oldest, most primitive and least altered types of meteorites, called chondrites, are especially adept at telling scientists what might have happened during these beginning stages of formation. Chondrite meteorites are actually pieces of asteroids that were broken off by collisions and have remained relatively unmodified for billions of years. They are mostly built of small stony grains, called chondrules.

It's these chondrules that can tell scientists a bit about the solar system. Chondrules themselves formed through quick melting events in the dusty gas cloud that surrounded the young sun. Patches of this so-called solar nebula heated above the melting point of rock for hours to days, and dustballs caught in these events made droplets of molten rock which then cooled and crystallized into chondrules.

In this case, the researches mapped the magnetic fields on chondrule grains from a meteorite named Semarkona. They found a magnetic field strength of around 54 microtesla, which is similar to the magnetic field on Earth's surface, which ranges from 25 to 65 microtesla.

Surprisingly, many previous measurements of meteorites also implied similar field strengths. This latest study also shows that chondrules are magnetized before they were built into the meteorite and not while sitting on Earth's surface.

"My modeling for the heating events shows that shock waves passing through the solar nebula is what melted most chondrules," said Desch. "Given the measured magnetic field strength of about 54 microtesla, this shows the background field in the nebula was probably in the range of 5 to 50 microtesla."

These findings reinforce the idea that shocks melted the chondrules in the solar nebula at about the location of today's asteroid belt. This, in turn, tells us a bit more about how our solar system formed.

The findings are published in the journal Science.