Obs. : 2012-09-19 Planet Ly alpha (photons/cm^2/sec) Mercury 4.646e+11 Venus 4.120e+11 Earth 4.438e+11 Mars 4.944e+11 Jupiter 4.018e+11 Saturn 4.917e+11 Uranus 4.228e+11 Neptune 4.438e+11 Pluto 4.725e+11