Obs. : 2010-04-21 Planet Ly alpha (photons/cm^2/sec) Mercury 3.744e+11 Venus 3.757e+11 Earth 3.721e+11 Mars 3.796e+11 Jupiter 3.547e+11 Saturn 3.746e+11 Uranus 3.547e+11 Neptune 3.517e+11 Pluto 3.598e+11