Spring Equinox Arrives March 20

The spring equinox arrives on March 20, marking the official start of the astronomical spring season in the Northern Hemisphere as the sun crosses directly over Earth's equator, bringing nearly equal lengths of daylight and darkness to locations around the world.

This celestial event, occurring at approximately 10:46 a.m. EDT, signals a shift in the planet's tilt relative to the sun, ushering in longer days that will continue to build until the summer solstice in June. According to astronomers, the equinox results from Earth's 23.5-degree axial tilt as it orbits the sun, positioning the equator in direct alignment with the sun's rays. While the term "equinox" derives from Latin words meaning "equal night," the day actually features slightly more daylight—about eight minutes longer at mid-temperate latitudes—due to the sun's apparent disk shape and atmospheric refraction, which bends sunlight and extends the periods of sunrise and sunset.

In the days leading up to March 20, observers in the Northern Hemisphere may notice the true moment of equal day and night, known as the equilux, which typically falls a few days earlier depending on latitude. For instance, in parts of the...