The moon stole something from the depths of Earth hundreds of millions of years ago, scientists can prove: Science Alert

Earth and its moon are unique in the solar system. Earth is the only planet with only one moon, and that moon is very influential. In fact, some studies suggest that life on Earth might not have arisen without the Moon.

Combine that with a size ratio unlike any other planet-moon system we’ve ever seen — the Moon is just over a quarter the size of Earth — and scientists are naturally interested in where the Moon came from.

Many, like a pair of potato-shaped rocks orbiting Mars, are captured asteroids.

Scientists, however, believe that the moon’s origin story is one of fire and fury: a massive collision with a Mars-sized planet called Theia that scooped up massive amounts of debris from the still-warm, barely-formed Earth. 4.5 billion years ago. The theory is that these pieces merged to form our satellite.

Now, we have new evidence that this violence was born.

Isotopes of the noble gases helium and neon captured in lunar meteorites recovered from Antarctica match those found in the solar wind, but were never exposed to it. This, along with the signature argon isotope concentration, suggests that these gases were inherited from Earth long ago, when the two objects were one.

“For the first time, solar gas unrelated to lunar surface exposure has been found in basalt material from the moon, and it’s such an exciting result,” said Patrizzi, a cosmochemist at ETH Zurich who is now at the University of Washington in Switzerland. Ya Weir said. St. Louis.

Directly studying the composition of the Moon is a complex undertaking. We haven’t been there since 1972 and collected very few samples.

The Moon does, however, occasionally come to us in the form of meteorites that are thrown in our direction when something big hits the surface.

A bunch of these lunar meteorites, or lunar meteorites, have been discovered; we know of hundreds of them, all over the world.

Weir and her colleagues studied just six fragments from Antarctica. These fragments are all part of the same protometeoroid, composed of a very specific kind of rock: breccia—that is, not the “fruitcake” of multiple rock types like many meteorites—from the lunar volcanic plains of basalt.

The rock formed when magma seeped upward from the Moon’s interior and cooled rapidly, being covered by more layers of basalt, shielding it from the surrounding environment — including cosmic rays and the solar wind. As the basalt cooled, volcanic glass particles formed and crystallized and remained beneath the lunar surface.

The rock lay there until an impact strong enough to send the moon rock toward Earth occurred. Such an impact must have been relatively large, reaching deep into the lunar surface to reach rocks that have not been exposed for hundreds of millions of years.

To find out their secrets, the research team studied the moonstones using a noble gas mass spectrometer at the Noble Gas Laboratory at ETH Zurich. The instrument is one of the most powerful in the world — and the only one capable of detection, the researchers say.

The team found that submillimeter glass grains in basalt retain the isotopic signatures of helium and neon, like tiny time capsules. These signatures are the same as the solar wind, but the detected abundances are much higher than expected.

Because basalt is not exposed to the solar wind, the gas must have come from elsewhere.

The team found that neon’s isotope ratios are very similar to those in Earth’s mantle plumes, deep upwellings of hot melt that sample reservoirs of material deep in the Earth that may have been around 4.5 billion years ago. Earth has not been disturbed since its formation. The researchers concluded that the similarity suggested that the gases came from Earth.

The discovery could spark interest in studying noble gases in meteorites and take a closer look at other substances that may be present in other lunar rocks that were previously undetectable but are now within reach, such as hydrogen and halogens.

“While these gases are not necessary for life, it would be interesting to understand how some of these noble gases survived the brutal and violent formation of the Moon,” says geochemist Henner Busemann of ETH Zurich.

“This knowledge may help scientists in the fields of geochemistry and geophysics create new models that show more generally how these most volatile elements survived planet formation in our solar system and beyond.”

The research has been published in scientific progress.

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