Obs. : 2013-02-20 Planet Ly alpha (photons/cm^2/sec) Mercury 4.210e+11 Venus 4.349e+11 Earth 4.128e+11 Mars 4.296e+11 Jupiter 4.052e+11 Saturn 4.091e+11 Uranus 4.121e+11 Neptune 4.349e+11 Pluto 4.191e+11