Obs. : 2008-07-04 Planet Ly alpha (photons/cm^2/sec) Mercury 3.491e+11 Venus 3.534e+11 Earth 3.446e+11 Mars 3.590e+11 Jupiter 3.472e+11 Saturn 3.590e+11 Uranus 3.387e+11 Neptune 3.417e+11 Pluto 3.521e+11