Obs. : 2009-12-23 Planet Ly alpha (photons/cm^2/sec) Mercury 3.563e+11 Venus 3.577e+11 Earth 3.614e+11 Mars 3.669e+11 Jupiter 3.520e+11 Saturn 3.634e+11 Uranus 3.481e+11 Neptune 3.520e+11 Pluto 3.577e+11