Obs. : 2009-02-28 Planet Ly alpha (photons/cm^2/sec) Mercury 3.440e+11 Venus 3.487e+11 Earth 3.456e+11 Mars 3.440e+11 Jupiter 3.440e+11 Saturn 3.416e+11 Uranus 3.511e+11 Neptune 3.440e+11 Pluto 3.355e+11