Vernal Equinox 2024 Uk. The vernal equinox — is an astronomical phenomenon when the sun, in its visible motion along the ecliptic, crosses the celestial equator. The spring equinox, or the vernal equinox as it is more formally known, marks the astronomical start of spring, when the sun passes north over the celestial equator, a notional equator that.

But did you know there are actually three main definitions for the season coming from astronomy, meteorology and phenology? The first day of spring in the uk astronomically occurs on the vernal equinox, 20 march 2025.