Obs. : 2013-09-20 Planet Ly alpha (photons/cm^2/sec) Mercury 3.542e+11 Venus 3.642e+11 Earth 3.906e+11 Mars 3.740e+11 Jupiter 3.798e+11 Saturn 3.642e+11 Uranus 3.873e+11 Neptune 3.893e+11 Pluto 4.026e+11