Obs. : 2009-05-23 Planet Ly alpha (photons/cm^2/sec) Mercury 3.626e+11 Venus 3.610e+11 Earth 3.520e+11 Mars 3.618e+11 Jupiter 3.532e+11 Saturn 3.580e+11 Uranus 3.577e+11 Neptune 3.532e+11 Pluto 3.520e+11