Obs. : 2009-01-13 Planet Ly alpha (photons/cm^2/sec) Mercury 3.585e+11 Venus 3.584e+11 Earth 3.525e+11 Mars 3.532e+11 Jupiter 3.585e+11 Saturn 3.483e+11 Uranus 3.584e+11 Neptune 3.598e+11 Pluto 3.479e+11