Obs. : 2009-06-23 Planet Ly alpha (photons/cm^2/sec) Mercury 3.549e+11 Venus 3.466e+11 Earth 3.477e+11 Mars 3.466e+11 Jupiter 3.420e+11 Saturn 3.701e+11 Uranus 3.416e+11 Neptune 3.420e+11 Pluto 3.578e+11