Obs. : 2009-10-16 Planet Ly alpha (photons/cm^2/sec) Mercury 3.453e+11 Venus 3.432e+11 Earth 3.526e+11 Mars 3.515e+11 Jupiter 3.592e+11 Saturn 3.432e+11 Uranus 3.529e+11 Neptune 3.592e+11 Pluto 3.654e+11