What Is Spring Equinox 2025. The first day of spring (march equinox or vernal equinox) is when the sun shines directly on the celestial equator passing from south to north and the length of day and night. During march it is springtime in the northern hemisphere and march equinox is called vernal equinox and spring equinox while it is an autumn time in the southern hemisphere and march.

Spring equinox 2025 (beginning of astronomical spring) on the day of the spring (march) equinox, the sun crosses the celestial equator, moving along the ecliptic. The page on variation in times of perihelion and aphelion.