Obs. : 2012-12-21 Planet Ly alpha (photons/cm^2/sec) Mercury 4.094e+11 Venus 4.140e+11 Earth 4.230e+11 Mars 4.091e+11 Jupiter 4.162e+11 Saturn 4.159e+11 Uranus 4.067e+11 Neptune 4.061e+11 Pluto 4.099e+11