Obs. : 2009-05-20 Planet Ly alpha (photons/cm^2/sec) Mercury 3.552e+11 Venus 3.580e+11 Earth 3.554e+11 Mars 3.565e+11 Jupiter 3.532e+11 Saturn 3.578e+11 Uranus 3.560e+11 Neptune 3.532e+11 Pluto 3.532e+11