Obs. : 2016-12-31 Planet Ly alpha (photons/cm^2/sec) Mercury 3.741e+11 Venus 3.693e+11 Earth 3.726e+11 Mars 3.693e+11 Jupiter 3.756e+11 Saturn 3.729e+11 Uranus 3.670e+11 Neptune 3.693e+11 Pluto 3.729e+11