Obs. : 2009-07-01 Planet Ly alpha (photons/cm^2/sec) Mercury 3.472e+11 Venus 3.441e+11 Earth 3.476e+11 Mars 3.429e+11 Jupiter 3.441e+11 Saturn 3.661e+11 Uranus 3.423e+11 Neptune 3.441e+11 Pluto 3.534e+11