Obs. : 2008-12-02 Planet Ly alpha (photons/cm^2/sec) Mercury 3.459e+11 Venus 3.484e+11 Earth 3.465e+11 Mars 3.459e+11 Jupiter 3.484e+11 Saturn 3.395e+11 Uranus 3.481e+11 Neptune 3.479e+11 Pluto 3.476e+11