Obs. : 2013-09-21 Planet Ly alpha (photons/cm^2/sec) Mercury 3.539e+11 Venus 3.595e+11 Earth 3.943e+11 Mars 3.825e+11 Jupiter 3.836e+11 Saturn 3.595e+11 Uranus 3.905e+11 Neptune 3.939e+11 Pluto 3.990e+11