Obs. : 2008-10-02 Planet Ly alpha (photons/cm^2/sec) Mercury 3.435e+11 Venus 3.522e+11 Earth 3.430e+11 Mars 3.495e+11 Jupiter 3.515e+11 Saturn 3.354e+11 Uranus 3.430e+11 Neptune 3.467e+11 Pluto 3.533e+11