Ancient meteorite granules still mystify scientists

Excerpt from the July, 16, 1966, issue of Science News

chondrules in a meteorite

ORIGINS UNKOWN  Tiny granules trapped inside meteorites (pictured in polarized light) are among the oldest solid objects in the solar system; researchers still debate how these chondrules formed.

James St. John/Wikimedia Commons (CC BY 2.0)

Lightning seen as cause of puzzling chondrules — Lightning flashes in the huge cloud of primeval dust and gas from which the planets in the solar system condensed may have caused formation of the puzzling objects known as chondrules … the tiny, rounded granules about the size of poppy seeds found in stony meteorites…. Dry lightning flashes could have been the source of the fast heating that, followed by quick cooling, [explains] the glassy structure of chondrules. — Science News, July 16, 1966


Chondrules are among the oldest pieces of planetary building blocks, formed roughly 4.6 billion years ago during the solar system’s first few million years. How they formed is still up for debate. But the lightning hypothesis has mostly fallen out of favor. One leading idea is that chondrules emerged in the wake of shock waves that rippled through the planet nursery. Those shock waves may have been triggered by collisions of embryonic planets, gas waves spiraling around the sun or strong solar flares.

Christopher Crockett is a freelance science writer and editor based in Arlington, Va. He has a Ph.D. in astronomy from the University of California, Los Angeles.

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