Changes in version 0.1.2 (2025-01-09) - Add function irrad_extraterrestrial() implementing estimation of the (shortwave) energy irradiance at the top of the atmosphere above a specific geographic location and at a given instant in time. The irradiance is estimated on a plane tangential to the surface of the "sphere" or Earth globe. Thus, it returns the solar constant corrected for the angle of incidence and for the current Earth-Sun distance. - Add on-line only article with accuracy and performance tests based on comparisons to alternatives. Changes in version 0.1.1 (2024-12-11) - Add function relative_AMt() implementing Young's (1994) AM approximation based on the true position of the sun. - Add relative_AM_geotime() and relative_AMt_geotime()as convenience wrapper functions. - Increase test coverage to nearly 95% with new tests and fix some minor bugs. - Fix bug in distance_to_sun(), the value returned was totally off-mark. Changes in version 0.1.0 - Package created as a spin-off from 'photobiology' by moving the astronomical computations related to the sun position, unchanged.