Obs. : 2013-12-29 Planet Ly alpha (photons/cm^2/sec) Mercury 4.205e+11 Venus 4.050e+11 Earth 3.910e+11 Mars 4.138e+11 Jupiter 3.900e+11 Saturn 4.325e+11 Uranus 3.725e+11 Neptune 3.810e+11 Pluto 4.205e+11