Obs. : 2009-10-10 Planet Ly alpha (photons/cm^2/sec) Mercury 3.475e+11 Venus 3.475e+11 Earth 3.486e+11 Mars 3.488e+11 Jupiter 3.582e+11 Saturn 3.475e+11 Uranus 3.486e+11 Neptune 3.539e+11 Pluto 3.681e+11