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Earth 'air' found on Moon
04/08/2005 07:02 - (SA)
Paris - The Moon's soil is impregnated with nitrogen that came from Earth's atmosphere, according to Japanese scientists writing on Thursday in Nature, the weekly British science journal.
The researchers, giving a new interpretative spin on analysis of lunar soil brought home by the Apollo missions, believe that the nitrogen escaped from Earth's upper atmosphere as charged atoms.
These ions then washed over the Moon, soon after Earth and its satellite were formed and were close together.
However, this could only have happened before Earth acquired its magnetic field, a phenomenon caused by a "dynamo" of liquid iron that began to circulate in the planet's core, they theorise.
The hypothesis could explain a long-running mystery about the Moon's surface.
The Moon was formed at high temperatures, and should thus be depleted in volatile elements, including nitrogen, carbon, hydrogen and the six "noble" gases, helium, neon, argon, krypton, radon and xenon.
However, all these elements have been found in the lunar soil, which suggests that the source came from elsewhere.
The paper is lead-authored by Minoru Ozima of the Graduate School of Earth and Planetary Science at the University of Tokyo.
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