Obs. : 2008-09-28 Planet Ly alpha (photons/cm^2/sec) Mercury 3.504e+11 Venus 3.504e+11 Earth 3.440e+11 Mars 3.504e+11 Jupiter 3.528e+11 Saturn 3.389e+11 Uranus 3.440e+11 Neptune 3.448e+11 Pluto 3.551e+11