Obs. : 2009-05-15 Planet Ly alpha (photons/cm^2/sec) Mercury 3.552e+11 Venus 3.477e+11 Earth 3.581e+11 Mars 3.477e+11 Jupiter 3.365e+11 Saturn 3.744e+11 Uranus 3.410e+11 Neptune 3.365e+11 Pluto 3.498e+11