Obs. : 2008-07-03 Planet Ly alpha (photons/cm^2/sec) Mercury 3.539e+11 Venus 3.574e+11 Earth 3.456e+11 Mars 3.628e+11 Jupiter 3.478e+11 Saturn 3.628e+11 Uranus 3.428e+11 Neptune 3.433e+11 Pluto 3.552e+11