Over the course of nearly five centuries, researchers put forward numerous, much debated theories as to how the Moon was formed. Now, researchers at ETH Zurich discover the first definitive proof that the Moon inherited indigenous noble gases from the Earth’s mantle. They show that the Moon inherited the indigenous noble gases of helium and neon from Earth’s mantle (Science Advances). The discovery adds to the already strong constraints on the currently favoured “Giant Impact” theory that hypothesises the Moon was formed by a massive collision between Earth and another celestial body.
The researchers analysed six samples of lunar meteorites — consisting of basalt rock that formed when magma welled up from the interior of the Moon and cooled quickly — from an Antarctic collection. The meteorites remained covered by additional basalt layers after their formation, which protected the rock from cosmic rays and, particularly, the solar wind. The cooling process resulted in the formation of lunar glass particles amongst the other minerals found in magma. They discovered that the glass particles retain the chemical fingerprints (isotopic signatures) of the solar gases: helium and neon from the Moon’s interior. Their findings strongly support that the Moon inherited noble gases indigenous to the Earth, says a press release.
Using a state-of-the-art noble gas mass spectrometer named “Tom Dooley” the researchers were able to measure sub-millimetre glass particles from the meteorites and rule out solar wind as the source of the detected gases. The helium and neon that they detected were in a much higher abundance than expected. The Tom Dooley was used to detect these noble gases in the seven-billion-year-old grains in the Murchison meteorite — the oldest known solid matter to-date.
