Obs. : 2008-12-09 Planet Ly alpha (photons/cm^2/sec) Mercury 3.501e+11 Venus 3.526e+11 Earth 3.470e+11 Mars 3.440e+11 Jupiter 3.526e+11 Saturn 3.404e+11 Uranus 3.475e+11 Neptune 3.499e+11 Pluto 3.501e+11