earth = { 'earth_radius': 6371e3, 'atmos_height': 100e3, 'rayleigh_atmos_height': 7994, 'mie_atmos_height' : 1200, 'rayleigh_beta': (5.4717e-6, 12.7853e-6, 31.2142e-6), 'mie_beta' : (21e-6), 'mie_g' : 0.75 }