Glass from the Trinity test site is helping us figure out the birth of our lunar companion
Radioactive glass left over from the first ever test of a nuclear bomb is providing scientists with clues about the formation of Earth’s Moon. This glassy bomb byproduct is revealing how certain materials may have evaporated from the Moon when it first took shape more than 4 billion years ago.
For decades now, the leading theory has been that our Moon formed when Earth was hit by a Mars-sized object dubbed Theia. This collision is thought to have been so strong and hot, that it caused certain types of chemicals known as volatiles — elements with really low melting points — to evaporate from the newly forming Moon. Researchers have been studying volatiles in Moon rocks for decades, in order to better understand how our lunar neighbor formed. They have speculated about how this evaporation process occurred, but it’s been difficult to back these theories up with empirical evidence. You’d need to re-create the same conditions of the Moon’s birth on an enormous scale.
That’s why researchers at the University of San Diego decided to use a nuclear test as a proxy for what the Moon experienced billions of years ago. “It dawned on me that if we’re going to use a big experiment, it needed to be something of sufficient size to see [this effect],” James Day, the lead author of a study published today in Science Advances and a geochemist at Scripps Institution of Oceanography at the University of California at San Diego, tells The Verge. “And I thought about it, and the Trinity test site would be the best place for this.”
The Trinity test is the first full-scale detonation of a nuclear bomb. In July 1945, the bomb exploded with a force of 84 terajoules in the New Mexico desert — a relatively small explosion compared to the nuclear weapons of today. Still, the heat of the Trinity blast was so intense that it melted the sands at the test site, creating a radioactive, green-colored glass that’s called trinitite. This strange glass extended from 1,000 to 1,600 feet in every direction from the center of the bomb’s blast.