Obs. : 2009-01-08 Planet Ly alpha (photons/cm^2/sec) Mercury 3.555e+11 Venus 3.525e+11 Earth 3.457e+11 Mars 3.482e+11 Jupiter 3.534e+11 Saturn 3.411e+11 Uranus 3.482e+11 Neptune 3.534e+11 Pluto 3.440e+11