Earth's oxygen has scattered to the moon over the past 2.4 billion years and is embedded in the lunar soil where it could hold clues about our planet's ancient atmosphere, according to new research from Japanese scientists.
The journal Science said small bits of oxygen leaks into space each day, and noted that some atoms and molecules near the top of Earth atmosphere actually move fast enough to escape Earth's gravitational pull. This material remains in a teardrop shaped region surrounding Earth called the magnetosphere.
Kentaro Terada, a cosmo-chemist at Osaka University in Toyonaka, Japan, said that for five days each month the magnetosphere passes over the moon, shielding it from solar particles and allowing particles from the Earth to take take root.
This phenomenon was detected by sensors on Japan's Kaguya probe that was orbiting the moon in 2008, reported Science. Researchers said that during each burst of oxygen picked up during this five-day period, "an estimated 26,000 ions per second passed through each square centimeter of sensor."
Details about the research were published Monday online in Nature Astronomy.
"Our new finding suggests that the Earth-Moon system co-evolves not only physically but also chemically," said Terada, lead author on the study, according to EOS Earth and Space News. He suggested that Moon dust could assist researchers in finding out more about Earth's ancient atmosphere.
Oxygen did not appear in significant amounts on Earth until about two billion years ago when aquatic creatures called cyanobacteria evolved and started converting carbon dioxide into sugar and oxygen molecules through photosynthesis, said EOS.
"We can't exactly go back and measure the Earth's atmosphere a billion years ago," said Jasper Halekas, a physicist at the University of Iowa in Iowa City who studies solar wind's effects on the solar system but was not connected to Terada's research, per EOS.
Halekas said the moon could be "a really useful thing to be able to look at if we want to understand how the Earth and its atmosphere evolved over time."
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