Provides functions and methods for estimating phenological dates (green up, start of a season, maturity, senescence, end of a season and dormancy) from (nearly) periodic Earth Observation time series. These dates are critical points of some derivatives of an idealized curve which, in turn, is obtained through a functional principal component analysis-based regression model. Some of the methods implemented here are based on T. Krivobokova, P. Serra and F. Rosales (2022) < https://www.sciencedirect.com/science/article/pii/S0167947322000998>. Methods for handling and plotting Earth observation time series are also provided.