Obs. : 2009-08-28 Planet Ly alpha (photons/cm^2/sec) Mercury 3.493e+11 Venus 3.468e+11 Earth 3.538e+11 Mars 3.484e+11 Jupiter 3.538e+11 Saturn 3.493e+11 Uranus 3.510e+11 Neptune 3.537e+11 Pluto 3.575e+11