Scientists have found an unusual way to test how the Moon formed – they looked at radioactive glass formed in the first nuclear explosion at the Trinity test site in New Mexico.
The team, led by Professor James Day from the University of California San Diego, analyzed the glass, known as trinitite, to understand exactly what happens to certain elements at extreme temperatures. The Moon is believed to have formed in a planetary collision between our planet and a Mars-sized object, and the impact is believed to have vaporized the materials that made our satellite.
In a paper published in Science Advances, the team discuss how the trinitite samples located closer to ground zero were depleted of lighter, more volatile elements such as zinc and tended to have heavier isotopes of these volatiles. These two properties are shared both by the nuclear rocks and the lunar ones.
"The results show that evaporation at high temperatures, similar to those at the beginning of planet formation, leads to the loss of volatile elements and to enrichment in heavy isotopes in the leftover materials from the event," said Professor Day in a statement. "This has been conventional wisdom, but now we have experimental evidence to show it."
Scientists have long suspected that a similar reaction took place in the formation of the Moon, but it’s obviously not easy to create the same conditions in the lab. The site of the plutonium bomb explosion offered a rare chance to see these extreme effects.
The ground zero of the Trinity test is covered in a thin sheet of this glass, which was named trinitite after the bomb. The team collected samples from between 10 meters (33 feet) and 250 meters away (820 feet) from the detonation point.
"We used what was a history-changing event to scientific benefit, obtaining new and important scientific information from an event over 70 years ago that changed human history forever," added Day.
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