Obs. : 2009-09-15 Planet Ly alpha (photons/cm^2/sec) Mercury 3.509e+11 Venus 3.402e+11 Earth 3.480e+11 Mars 3.425e+11 Jupiter 3.504e+11 Saturn 3.509e+11 Uranus 3.439e+11 Neptune 3.480e+11 Pluto 3.609e+11