We are all made of tiny balls — trillions upon trillions of chondrules that formed before the planets.
“In our understanding of how Earth came to be, there may be nothing as important as the mystery of the chondrule.” — SciAm March 2021
Meteorite by Tim Gregory is one of the best non-fiction books I have ever read. It describes in sculpted prose how scientists have explored the mysteries of our solar system’s formation and dated the age of the Earth using the ancient time capsules that routinely rain on Earth — meteorites. Here are some of my favorite passages:
“Asteroids are not fragments of a shattered planet; they are fragments that never formed a planet in the first place.” (49)
“Billowing through the protoplanetary disc as a mass of brightly glowing droplets of lava, clouds of freshly sintered chondrule grains swarmed for five million years. Trillions upon trillions of chondrules, in numbers that far exceed the number of stars in the observable Universe, spiraled as gravitational vortices, and coalesced to build the asteroids and the planets. What a sight it must have been.” (p.140)
“The CAIs and chondrules (the circular grains) beautifully preserve pieces of cosmic sediment that formed in the collapsing nebula of our Solar System. The white CAIs are crystals formed directly from the nebular gas; they would resemble snowflakes growing out of thin air. They hold an exotic blend of oxygen isotopes unknown on Earth. Our sun has the exact same blend of oxygen isotopes. The CAIs formed next to the sun at 1,400°F like primordial white Sun snow. Stellar gusts from the surface of the sun blew the CAIs far outward to the colder distal regions of the protoplanetary disc. Scientist Sorby deduced their origin and called them “drops of fiery rain” in 1877. These small spheres formed separately over 5 million years, and they agglomerated over time.”
“Some of the grains come from other solar systems that popped like supernova firecrackers in our midst. The diamond and silicon carbide grains “crystallized around other stars. They are pieces of bona fide stardust. Some pre-date the solar system by over three billion years! Tiny pieces of rock that are seven billion years old! The mind boggles. We call these most remarkable motes of cosmic sediment ‘pre-solar’ grains.” (p.179)
“Draped like glowing tapestries, the ejecta from a supernova explosion decorate the ocean of interstellar space.” (161)
“There is an epic written inside every piece of meteorite.” (130)
P.S. The oldest rock ever dated is the CAI called “SJ101” – 4.567 billion years old!
Here are my photos of my chondrites, including some 5x macro zooms from my collection to bring it to life. And here are the author’s favorite meteorite photos and thin slices. His book is available at Amazon
And from the current SciAm, March 2021:
“Understanding chondrule formation could reveal our solar system’s earliest moments. And now, with fresh or prospective results from missions such as Hayabusa2 as well as other avenues of research, chondrule-obsessed scientists are on the cusp of answering the long-standing question of where they—and perhaps we—came from. “They are stained- glass windows to the earliest time period of the solar system,” says Harold Connolly, a cosmochemist and chondrule expert at Rowan University. “They are witnesses to processes that operated in the early solar system. The question is, What did they witness?”
For chondrules to form, dust must have been heated to temperatures of up to 2,000 degrees°C by some process in the early solar system, before rapidly cooling over just days or even hours. This process, whatever it was, most likely occurred throughout the solar system; that seems to be the only way to account for the large abundance of chondrules.
Hayabusa2 is not the only sample-return mission with extraterrestrial gifts in store for chondrule scientists. NASA’s OSIRIS-REx spacecraft is scheduled to re- turn to Earth in September 2023 with recently acquired samples of another asteroid, called Bennu, that are expected to be chondrule-rich.”
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