Spring Solstice 2024 Calendario. An equinox is one of two days in the year when the sun crosses the equator and day and night become equal in length. The june solstice marks the first day of astronomical summer in the northern hemisphere and the first day of winter in the southern hemisphere.

Many people mark it as the first day of the spring. The equinoxes occur around march 20 and september 22 each year, corresponding to an equal length of day and night.