Equinoxe and solstice times - rhannequin/astronoby GitHub Wiki

The equinox and solstice are two precise events that each happen twice a year.

The equinox is the time when the Sun appears directly above the equator, the solstice is the time when the Sun reaches its most northerly or southerly excursion relative to the celestial equator on the celestial sphere.

Astronoby enables to compute the time of each of these four events .

ephem = Astronoby::Ephem.load("inpop19a.bsp")

Astronoby::EquinoxSolstice.march_equinox(2025, ephem)
# => 2025-03-20 09:01:29 UTC

Astronoby::EquinoxSolstice.june_solstice(2025, ephem)
# => 2025-06-21 02:42:19 UTC

Astronoby::EquinoxSolstice.september_equinox(2025, ephem)
# => 2025-09-22 18:19:22 UTC

Astronoby::EquinoxSolstice.december_solstice(2025, ephem)
# => 2025-12-21 15:03:03 UTC