Obs. : 2009-01-06 Planet Ly alpha (photons/cm^2/sec) Mercury 3.511e+11 Venus 3.478e+11 Earth 3.443e+11 Mars 3.458e+11 Jupiter 3.499e+11 Saturn 3.389e+11 Uranus 3.474e+11 Neptune 3.499e+11 Pluto 3.420e+11