Obs. : 2009-05-27 Planet Ly alpha (photons/cm^2/sec) Mercury 3.616e+11 Venus 3.556e+11 Earth 3.467e+11 Mars 3.582e+11 Jupiter 3.440e+11 Saturn 3.630e+11 Uranus 3.501e+11 Neptune 3.440e+11 Pluto 3.467e+11