According to new research, our planet has been bombarding oxygen atoms to the lunar surface for billions of years. An estimated 4 trillion trillion trillion atoms of oxygen have been embedded in the moon  in the last 2.4 billion years or so. The finding was made by the observations of Japan’s moon-orbiting Kaguya spacecraft, which suggest that oxygen from Earth’s upper atmosphere is being sent to the moon’s surface for a few days each month.

The Japanese scientists explained their finding online in Nature Astronomy that a small bit of Earth’s air leaks into space each day. Some of the oxygen atoms and molecules at the top of our atmosphere move so fast that they overcome Earth’s gravitational pull. Our planet's magnetic field also drive the charged particles to be accelerated to even higher speed.

In effect, the moon is bombarded with high-speed, highly charged atoms each month. However, when the Earth’s magnetosphere passes over the moon for 5 days every month, this shields the moon from the solar particles, explaines Kentaro Terada, a cosmochemist at Osaka University. "Moon-orbiting probes experience the same conditions", he notes, the Science News  says.

The recent information provided by researchers have cleared a lot of questions regarding the observations. Mahes Anand, another cosmochemist at The Open University in the U.K have remarked of the online report. He comments that for years, no one has ever come up with a convincing explanation for how anomalies like that could occur in lunar soil.  

According to the Science Mag, the phenomenon was first spotted In 2008 when sensors onboard Japan’s Kaguya, a space craft designed to probe the moon, detected a drastic change in the types of oxygen ions crashing against the craft on specific times each month. The ions were slow moving than those typically carried by the solar wind and only has a single positive charge. These factors indicated that the oxygen atoms originated from earth.