Scientists makefirstdirect measurement of lunar backscatter from Solar Wind

A team of scientists has for the first time observed energetic neutral atoms scattered off the Moon from the incoming solar wind ion beam.
When the solar wind, made up mostly of ionized hydrogen, hits the Moon, most of it is absorbed, but some is reemitted as energetic neutral atoms.
This lunar backscatter and neutralization had been predicted but not directly measured until now.
Using NASA's Interstellar Boundary Explorer satellite, launched on 19 October 2008, D. J. McComas and colleagues from Southwest Research Institute, San Antonio, Texas, US, have for the first time made the measurement of this lunar backscatter from solar wind.
They found that about 10 percent of solar wind ions hitting the Moon result in the emission of neutral atoms, corresponding to about 150 metric tons of hydrogen emitted from the Moon per year.
They also showed that the energy spectrum and numbers of neutral atoms emitted from the Moon trace the variations in the incident solar wind.
The researchers suggest that the findings could shed additional light on the solar wind's interactions with other objects in the solar system, such as dust grains, asteroids, and moons of other planets, and could provide clues to the evolution of dust and rocky moons in other planetary systems.