Obs. : 2009-01-01 Planet Ly alpha (photons/cm^2/sec) Mercury 3.519e+11 Venus 3.496e+11 Earth 3.464e+11 Mars 3.466e+11 Jupiter 3.519e+11 Saturn 3.411e+11 Uranus 3.501e+11 Neptune 3.518e+11 Pluto 3.466e+11