Obs. : 2009-09-19 Planet Ly alpha (photons/cm^2/sec) Mercury 3.425e+11 Venus 3.304e+11 Earth 3.487e+11 Mars 3.360e+11 Jupiter 3.522e+11 Saturn 3.326e+11 Uranus 3.480e+11 Neptune 3.522e+11 Pluto 3.620e+11