Obs. : 2009-03-12 Planet Ly alpha (photons/cm^2/sec) Mercury 3.461e+11 Venus 3.539e+11 Earth 3.457e+11 Mars 3.461e+11 Jupiter 3.392e+11 Saturn 3.403e+11 Uranus 3.572e+11 Neptune 3.461e+11 Pluto 3.312e+11