Obs. : 2009-04-17 Planet Ly alpha (photons/cm^2/sec) Mercury 3.589e+11 Venus 3.486e+11 Earth 3.500e+11 Mars 3.436e+11 Jupiter 3.360e+11 Saturn 3.515e+11 Uranus 3.436e+11 Neptune 3.360e+11 Pluto 3.365e+11