Obs. : 2009-10-23 Planet Ly alpha (photons/cm^2/sec) Mercury 3.387e+11 Venus 3.377e+11 Earth 3.599e+11 Mars 3.523e+11 Jupiter 3.617e+11 Saturn 3.408e+11 Uranus 3.596e+11 Neptune 3.617e+11 Pluto 3.586e+11