New Evidence Points to the Moon Once Being Part of Earth

The moon may have originated from material pushed from Earth during a planetary collision, according to gases trapped in lunar meteorites.

ABOUT 4.5 BILLION YEARS AGO, a molten lava-covered primitive Earth circled the sun. It had only just begun to exist when it was violently impacted by Theia, a smaller object of Mars' size. The crash destroyed Theia and sent a sizable portion of Earth hurtling into space.

This debris whirled around Earth due to the planet's remaining mass's gravitational attraction. Some of the debris stayed together and produced the moon in a shockingly little period of time—possibly less than 100 years.

At least, this is how one well-liked hypothesis about the creation of the moon goes. However, there is new evidence that points to the possibility that the moon was really formed from the ruins of this cosmic collision billions of years ago. The notion is supported by the finding of certain gases inside the moon, which also provides us with crucial new information about how it may have occurred.

Patrizia Will researched six lunar meteorites that NASA had brought back from Antarctica in the early 2000s while pursuing her PhD at the Swiss Federal Institute of Technology (ETH) in Zurich. She and her coworkers discovered helium and neon trapped in microscopic glass beads in these rocks, which were created in volcanic eruptions on the lunar surface when magma was drawn up from the moon's core. These gases, which are referred to as noble gases because they are generally non-reactive, appear to have come from Earth and were probably passed on to the moon "during its development," according to Will. Science Advances, a publication, published the study.

The huge impact theory has been mentioned in earlier research. The extraordinary resemblance between Earth rocks and lunar rocks points to a shared origin. But there are important distinctions: For instance, lunar rocks contain a lighter form of chlorine, indicating a cataclysmic event that separated some material early in the histories of our two planets.

Now, most scientists concur that this was a massive collision. Sujoy Mukhopadhyay, a geochemist at the University of California, Davis who was not part in Will's work, states, "We are quite set on the massive impact idea. The most promising theory is still the one.

After the collision, a disk of material that had been moved by it may have formed around our planet. This disk may have included a donut-shaped chunk of rock that had been vaporized and reached temperatures of thousands of degrees, known as a synestia. The relative abundance of these gases suggests they originated from Earth's mantle and were launched into space by the impact before being fused into the interior of our satellite. The quantity of neon and helium found in the lunar samples also supports the idea that the moon formed in this synestia. We would anticipate that the concentrations of these gases in the meteorites under study would be far smaller if they had instead been carried onto the moon by solar winds from across space.

No previous research has been able to detect evidence for such indigenous gases in lunar rocks, therefore Mukhopadhyay calls it "very exciting work." Ray Burgess, a geochemist from the University of Manchester and a reviewer of Will's research, claims that the quantities are extremely low and hence very difficult to detect. It's a significant improvement.

The Noble Gas Laboratory at ETH Zurich is home to a cutting-edge mass spectrometer that can identify the components of a chemical compound by weighing each of its constituent molecules. Will and her team used this device to make the finding. Will claims that the ETH Zurich equipment "has the highest sensitivity for researching helium and neon" in the whole globe. By using a small pair of tweezers to remove the glass beads from the meteorites, the researchers were able to examine the composition of the beads under a microscope and discover minute amounts of helium and neon trapped inside. The glass beads themselves were "very small, microscopic grains," according to Will, measuring only millionths of a meter.

The next stage is to comprehend where Earth's noble gases came from. There are two basic hypotheses: either Earth physically drew them into its atmosphere from the cloud of gas and dust that encircled our young sun, or they were transported by comets and asteroids that smashed into our protoplanet. Krypton and xenon are two other noble gases that researchers hope to detect in lunar meteorites to help them answer this question.

Other meteorites that have collided with our planet contain krypton and xenon, which are fragments of asteroids that may have served as the building blocks of planets like Earth in the past. If such gases are present in lunar meteorites as well, we will be able to compare their compositions and "see the relationship," according to Burgess. Because they provide a more accurate account of the early history of the solar system, lunar meteorites should be studied rather than only rocks on Earth.

It would support the hypothesis that our noble gases came from asteroids and comets if krypton and xenon discovered in lunar meteorites are identical to those found in meteorites from other places; if not, it would support the nebula theory. Burgess continues, "It would be a fascinating conundrum that we'd have to work out" if we don't discover any krypton or xenon.

The researchers found traces of krypton and xenon in the lunar meteorite samples they examined, according to Henner Busemann from ETH Zurich, a collaborator on Will's work, but they were unable to confirm their findings. He states, "We cannot make the case just now. "We'll aim to obtain greater accuracy now."

We may learn more about the moon's water content if we discover noble gases there. Water might have survived the moon's tumultuous genesis if hydrogen and neon did, and there is evidence for this from the water that has frozen as ice near the moon's poles. Such water could prove to be a priceless asset for upcoming human missions. The possibility of discovering resources that humans would wish to exploit increases if the moon is wetter than previously imagined, according to Burgess.

This may imply that a range of life-forming substances may endure massive impacts early in a planet's existence. Will adds, "We could develop new models regarding this planetary formation process in the solar system and beyond," adding that this may be a factor in the creation of life on Earth and maybe other worlds as well.