Obs. : 2009-01-20 Planet Ly alpha (photons/cm^2/sec) Mercury 3.463e+11 Venus 3.425e+11 Earth 3.470e+11 Mars 3.463e+11 Jupiter 3.479e+11 Saturn 3.413e+11 Uranus 3.425e+11 Neptune 3.474e+11 Pluto 3.379e+11