By Hamish Johnston at the AAS meeting in Seattle
You know it has been a good day when you learn a new amazing fact.
Today I discovered that the Moon is brighter than the Sun when it comes to gamma radiation.
How can a cold lump of rock give off more gamma radiation than a seething fusion reactor?
The answer, according to NASA’s Julie McEnery, is that both bodies glow with gammas because they are illuminated by cosmic radiation. The Sun’s strong magnetic field deflects much of this radiation away from the star. The Moon, however, has an extremely weak field that is not much use at deflecting cosmic rays.