Obs. : 2012-04-23 Planet Ly alpha (photons/cm^2/sec) Mercury 4.217e+11 Venus 4.157e+11 Earth 4.392e+11 Mars 4.171e+11 Jupiter 4.170e+11 Saturn 4.343e+11 Uranus 4.217e+11 Neptune 4.387e+11 Pluto 4.386e+11