Tools Astrocalculator Equinoxes and Solstices module The Equinoxes and Solstices calculator module Equinoxes and Solstices The Equinoxes and Solstices module calculates the date and time of an equinox or solstice for a given year. You specify which event (Spring Equinox, Summer Solstice, Autumn Equinox or Winter Solstice) should be investigated, and the year. Then press the Compute button to obtain the date and time of the event, and the length of the corresponding season, in days. There is a batch mode for this module. To use it, simply generate an input file whose lines each contain a year for which the Equinox and Solstice data will be computed. Then specify the input and output filenames, and press the Run button to generate the output file. Each line in the output file contains the input year, the date and time of each event, and the length of each season.