Obs. : 2009-09-04 Planet Ly alpha (photons/cm^2/sec) Mercury 3.435e+11 Venus 3.347e+11 Earth 3.469e+11 Mars 3.414e+11 Jupiter 3.469e+11 Saturn 3.353e+11 Uranus 3.433e+11 Neptune 3.469e+11 Pluto 3.521e+11