Obs. : 2010-04-18 Planet Ly alpha (photons/cm^2/sec) Mercury 3.832e+11 Venus 3.848e+11 Earth 3.672e+11 Mars 3.781e+11 Jupiter 3.640e+11 Saturn 3.714e+11 Uranus 3.640e+11 Neptune 3.587e+11 Pluto 3.542e+11