The Meaning of Spring Equinox and Traditions From Around the World On 3/17/21 at 1:35 PM EDT The spring equinox in the Northern Hemisphere is almost upon us. This event marks the moment when the sun crosses the celestial equator—an imaginary line in the sky above the Earth's equator—from south to north. In 2021, it occurs on March 20 at 5:37 a.m. ET, or 2:37 a.m. in the Pacific time zone. Read more aequus and nox, which mean "equal" and "night" respectively. On the March equinox, the length of the day and night is almost equal wherever you are in the world, with the sun shining directly on the equator. This is also the case for the other equinox in September.