Obs. : 2010-02-17 Planet Ly alpha (photons/cm^2/sec) Mercury 3.867e+11 Venus 3.805e+11 Earth 3.774e+11 Mars 3.779e+11 Jupiter 3.805e+11 Saturn 3.815e+11 Uranus 3.780e+11 Neptune 3.863e+11 Pluto 3.867e+11