Obs. : 2009-10-01 Planet Ly alpha (photons/cm^2/sec) Mercury 3.480e+11 Venus 3.480e+11 Earth 3.510e+11 Mars 3.559e+11 Jupiter 3.507e+11 Saturn 3.460e+11 Uranus 3.510e+11 Neptune 3.507e+11 Pluto 3.571e+11