Obs. : 2012-04-16 Planet Ly alpha (photons/cm^2/sec) Mercury 4.011e+11 Venus 4.108e+11 Earth 4.200e+11 Mars 4.382e+11 Jupiter 4.045e+11 Saturn 4.254e+11 Uranus 4.011e+11 Neptune 4.053e+11 Pluto 3.931e+11