Obs. : 2009-01-30 Planet Ly alpha (photons/cm^2/sec) Mercury 3.478e+11 Venus 3.480e+11 Earth 3.444e+11 Mars 3.518e+11 Jupiter 3.518e+11 Saturn 3.405e+11 Uranus 3.515e+11 Neptune 3.513e+11 Pluto 3.411e+11