Obs. : 2010-01-31 Planet Ly alpha (photons/cm^2/sec) Mercury 3.613e+11 Venus 3.785e+11 Earth 3.555e+11 Mars 3.555e+11 Jupiter 3.808e+11 Saturn 3.502e+11 Uranus 3.767e+11 Neptune 3.785e+11 Pluto 3.560e+11