Obs. : 2009-10-09 Planet Ly alpha (photons/cm^2/sec) Mercury 3.472e+11 Venus 3.472e+11 Earth 3.446e+11 Mars 3.478e+11 Jupiter 3.499e+11 Saturn 3.472e+11 Uranus 3.446e+11 Neptune 3.499e+11 Pluto 3.644e+11