Obs. : 2009-05-17 Planet Ly alpha (photons/cm^2/sec) Mercury 3.484e+11 Venus 3.509e+11 Earth 3.600e+11 Mars 3.509e+11 Jupiter 3.449e+11 Saturn 3.673e+11 Uranus 3.453e+11 Neptune 3.449e+11 Pluto 3.499e+11