Sulla luna il problema dal punto di vista radioattivo sarebbe potuto essere il sole e le sue tempeste magnetiche.

Session 25 - Solar System.
Oral session, Monday, January 13
Piers 2/3,
[25.02] EGRET Detection of Gamma Rays from the Moon
D. J. Thompson, D. L. Bertsch (NASA/GSFC), D. J. Morris (UNH), R. Mukherjee (NASA/GSFC/USRA)

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has detected gamma rays from the Moon as it passed through the instrument field of view several times between 1991 and 1994. The average flux, (4.7 \pm 0.7) \times 10^-7 ph(>100 MeV)/cm^2s, and the energy spectrum of the lunar gamma radiation are consistent with a model of gamma ray production by cosmic ray interactions with the lunar surface, and the flux varies as expected with the solar cycle. Although the same processes may occur on the Sun, EGRET does not detect the quiet Sun. The upper limit, 3.0 \times 10^-7 ph(>100 MeV)/cm^2s, does not contradict calculations of the expected solar gamma-ray flux. Thus, in high-energy gamma rays, the Moon is brighter than the quiet Sun.

Gamma glow from the moon.(images from Compton Gamma Ray Observatory indicate moon's gamma rays are stronger than those of the sun)(Brief Article)

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Science News

Science News; 1/25/1997; Cowen, Ron

Viewed at wavelengths from visible light to X rays, the sun is our solar system's star performer. Observed in the light of gamma rays, however, the moon outdazzles the sun. Images taken recently by a telescope aboard the Comp-ton Gamma Ray Observatory (GRO) provide graphic evidence of this phenomenon. "As far as we know, no other branch of astronomy sees the moon brighter than the sun," says GRO investigator David J. Thompson of NASA's Goddard Space Flight Center in Greenbelt, Md.

The gamma glow occurs when high-energy cosmic rays-the charged particles streaming in from distant regions of the galaxy at nearly the speed of light- smash into the moon. They excite the nuclei of atoms on the lunar sur-face, which then emit gamma radiation.