Obs. : 2017-12-20 Planet Ly alpha (photons/cm^2/sec) Mercury 3.676e+11 Venus 3.664e+11 Earth 3.718e+11 Mars 3.685e+11 Jupiter 3.679e+11 Saturn 3.666e+11 Uranus 3.680e+11 Neptune 3.667e+11 Pluto 3.662e+11