lit_fraction

nyx.emitter.moon.lit_fraction(alt_rad, disc_radius_rad=0.0, scale_height_km=8.0)

Fraction of the scattering column above the observer still lit.

Parameters:

• alt_rad (float) – Altitude of the body’s centre, in radians.

• disc_radius_rad (float) – Angular radius of the body; half its disc is still lit one radius below the geometric horizon.

• scale_height_km (float) – Scale height of the scattering column.

Returns:

One above the horizon, falling off as exp(-z_shadow / H) below it, and underflowing to zero well before the antipode.

Return type:

float