Obs. : 2011-09-20 Planet Ly alpha (photons/cm^2/sec) Mercury 4.533e+11 Venus 4.548e+11 Earth 4.435e+11 Mars 4.517e+11 Jupiter 4.391e+11 Saturn 4.508e+11 Uranus 4.403e+11 Neptune 4.435e+11 Pluto 4.560e+11