Obs. : 2009-05-16 Planet Ly alpha (photons/cm^2/sec) Mercury 3.606e+11 Venus 3.494e+11 Earth 3.600e+11 Mars 3.494e+11 Jupiter 3.421e+11 Saturn 3.727e+11 Uranus 3.416e+11 Neptune 3.421e+11 Pluto 3.503e+11