Obs. : 2008-10-21 Planet Ly alpha (photons/cm^2/sec) Mercury 3.414e+11 Venus 3.529e+11 Earth 3.467e+11 Mars 3.480e+11 Jupiter 3.518e+11 Saturn 3.431e+11 Uranus 3.461e+11 Neptune 3.484e+11 Pluto 3.541e+11