Obs. : 2017-12-18 Planet Ly alpha (photons/cm^2/sec) Mercury 3.787e+11 Venus 3.787e+11 Earth 3.877e+11 Mars 3.764e+11 Jupiter 3.761e+11 Saturn 3.816e+11 Uranus 3.852e+11 Neptune 3.843e+11 Pluto 3.819e+11