Oxygen has been leaking to the lunar surface from Earth for billions of years. Researchers have revealed that oxygen atoms from Earth have been traveling to the moon for about 2.4 billion years. Approximately, four trillion of oxygen atoms have built up in the moon's soil and rocks.
According to Science Mag, every day the Earth emits drops and bits of Oxygen into the atmosphere that ultimately reach the moon. Of the total five quadrillion metric tons of oxygen atoms, 90 metric tons have leaked from the Earth's atmosphere, escaping the pull of gravity. Oxygen atoms and molecules escape at a very fast speed and later converge in the space that engulfs the planet.
According to Scientific American, plants may be the main source of oxygen on Earth. In a new study, a team of Japanese researchers from Osaka University discovered that oxygen on the Earth was produced by plants through photosynthesis. Therefore, it can be deduced that the moon must have been the recipient of the oxygen from the planet's living plants.
In 2007, using the Ion Energy Analyzer (IEA) and the Ion Mass Analyzer (IMA), the Japan Aerospace Exploration Agency compared the Earth and the moon's charged atoms. As the moon revolves around the Earth and the sun, charged atoms from Earth are bound to land on the moon.