Obs. : 2009-08-27 Planet Ly alpha (photons/cm^2/sec) Mercury 3.450e+11 Venus 3.438e+11 Earth 3.517e+11 Mars 3.468e+11 Jupiter 3.512e+11 Saturn 3.450e+11 Uranus 3.497e+11 Neptune 3.512e+11 Pluto 3.548e+11