Obs. : 2009-08-30 Planet Ly alpha (photons/cm^2/sec) Mercury 3.422e+11 Venus 3.377e+11 Earth 3.477e+11 Mars 3.412e+11 Jupiter 3.477e+11 Saturn 3.369e+11 Uranus 3.431e+11 Neptune 3.471e+11 Pluto 3.506e+11