Obs. : 2009-09-22 Planet Ly alpha (photons/cm^2/sec) Mercury 3.297e+11 Venus 3.282e+11 Earth 3.527e+11 Mars 3.339e+11 Jupiter 3.533e+11 Saturn 3.297e+11 Uranus 3.497e+11 Neptune 3.533e+11 Pluto 3.621e+11