Obs. : 2009-08-16 Planet Ly alpha (photons/cm^2/sec) Mercury 3.366e+11 Venus 3.318e+11 Earth 3.475e+11 Mars 3.311e+11 Jupiter 3.475e+11 Saturn 3.366e+11 Uranus 3.385e+11 Neptune 3.440e+11 Pluto 3.463e+11