Obs. : 2009-12-08 Planet Ly alpha (photons/cm^2/sec) Mercury 3.721e+11 Venus 3.549e+11 Earth 3.504e+11 Mars 3.420e+11 Jupiter 3.699e+11 Saturn 3.377e+11 Uranus 3.643e+11 Neptune 3.699e+11 Pluto 3.638e+11