Obs. : 2008-12-29 Planet Ly alpha (photons/cm^2/sec) Mercury 3.517e+11 Venus 3.510e+11 Earth 3.495e+11 Mars 3.465e+11 Jupiter 3.517e+11 Saturn 3.433e+11 Uranus 3.500e+11 Neptune 3.517e+11 Pluto 3.465e+11