I have to admit, most of what I learned in elementary and middle school has either just been incorporated into my knowledge base or utterly forgotten. There are a few things I seem destined to never forget, like the Kookaburra song I learned in second grade when we studied Australia. And, much more usefully, the lessons we did on magnets in sixth grade. 

I distinctly remember learning that new magnets can be made in three different ways: you can pound on something containing iron and similar elements until all the minerals are shocked into aligning and making a magnet. You can store an existing magnet with something metal, and let the magnet’s field slowly turn the metal item into a magnet; this is something a lot of grandmas taught their grandkids to do with scissors to make it easy to pick up needles. You can also run electricity through loops of wire, or orbit charged particles, and make an electromagnet. These are all a lot of fun and perfect activities for sixth graders… and early solar systems.

Baby solar systems may have magnetic field forming disks. These die off as planets start forming and stars settle down a bit. Then the collisions start — the kinds of collisions that can generate magnetic fields in rocks and send objects flying across the solar system. And it’s kind of awesome.

In new research looking at samples of the Tagish Lake Meteorite, scientists were able to use these smash-induced magnetic fields to study the history of this particular space rock. Chemical analysis indicates the Tagish Lake Meteorite started its life somewhere out in the Kuiper belt, near or beyond the modern orbit of Neptune. This happened early on – just three million years or so after the solar system began to form and before Jupiter really started its reign. Once Jupiter came along, it started rearranging the solar system with its gravity, and this yanked the rock that would one day hit Earth out of the Kuiper belt and moved it into the asteroid belt.

This wasn’t an easy transition. It appears that that the rock was heated to 250˚C through a combination of the decay of radioactive minerals and an orbit-changing collision. This combo produced a lasting magnetic field. How the space rock made it from the asteroid belt to Earth is still a mystery, but whatever happened, it brought us some super cool data. According to lead scientist Yuki Kimura: Our results help us infer the early dynamics of Solar System bodies that occurred several million years after the formation of the Solar System, and imply a highly efficient formation of the outer bodies of the Solar System, including Jupiter. 

These results appear in The Astrophysical Journal Letters.

More Information

Hokkaido University press release

“Electron Holography Details the Tagish Lake Parent Body and Implies Early Planetary Dynamics of the Solar System,” Yuki Kimura, Kazuo Yamamoto, and Shigeru Wakita, 2021 August 11, The Astrophysical Journal Letters