Obs. : 2009-10-19 Planet Ly alpha (photons/cm^2/sec) Mercury 3.379e+11 Venus 3.380e+11 Earth 3.570e+11 Mars 3.492e+11 Jupiter 3.612e+11 Saturn 3.380e+11 Uranus 3.564e+11 Neptune 3.612e+11 Pluto 3.652e+11