Obs. : 2009-01-05 Planet Ly alpha (photons/cm^2/sec) Mercury 3.588e+11 Venus 3.541e+11 Earth 3.513e+11 Mars 3.528e+11 Jupiter 3.568e+11 Saturn 3.438e+11 Uranus 3.521e+11 Neptune 3.566e+11 Pluto 3.477e+11