Obs. : 2011-08-28 Planet Ly alpha (photons/cm^2/sec) Mercury 4.016e+11 Venus 4.000e+11 Earth 4.147e+11 Mars 4.103e+11 Jupiter 4.132e+11 Saturn 4.038e+11 Uranus 4.083e+11 Neptune 4.117e+11 Pluto 4.171e+11