Obs. : 2009-08-23 Planet Ly alpha (photons/cm^2/sec) Mercury 3.441e+11 Venus 3.409e+11 Earth 3.450e+11 Mars 3.420e+11 Jupiter 3.450e+11 Saturn 3.441e+11 Uranus 3.430e+11 Neptune 3.450e+11 Pluto 3.506e+11