Starship Asterisk*

Study suggests the rare objects likely came from an early planetesimal with a magnetic core.

Samples from a rare meteorite family, including the one shown here, reveal that their parent planetesimal, formed in the earliest stages of the solar system, was a complex, layered object, with a molten core and solid crust similar to Earth. Credit: Carl Agee, Institute of Meteoritics, University of New Mexico. Background edited by MIT News.

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Most meteorites that have landed on Earth are fragments of planetesimals, the very earliest protoplanetary bodies in the solar system. Scientists have thought that these primordial bodies either completely melted early in their history or remained as piles of unmelted rubble.

But a family of meteorites has befuddled researchers since its discovery in the 1960s. The diverse fragments, found all over the world, seem to have broken off from the same primordial body, and yet the makeup of these meteorites indicates that their parent must have been a puzzling chimera that was both melted and unmelted.

Now researchers at MIT and elsewhere have determined that the parent body of these rare meteorites was indeed a multilayered, differentiated object that likely had a liquid metallic core. This core was substantial enough to generate a magnetic field that may have been as strong as Earth’s magnetic field is today.

Their results ... suggest that the diversity of the earliest objects in the solar system may have been more complex than scientists had assumed. ...

• Science Advances 6(30):aba1303 (24 Jul 2020) DOI: 10.1126/sciadv.aba1303

... the parent body of these rare meteorites was indeed a multilayered, differentiated object that likely had a liquid metallic core. This core was substantial enough to generate a magnetic field that may have been as strong as Earth’s magnetic field is today.