Obs. : 2009-04-11 Planet Ly alpha (photons/cm^2/sec) Mercury 3.601e+11 Venus 3.532e+11 Earth 3.458e+11 Mars 3.454e+11 Jupiter 3.380e+11 Saturn 3.463e+11 Uranus 3.532e+11 Neptune 3.398e+11 Pluto 3.359e+11