Spring Equinox: Day & Night Nearly Equal

• Spring begins Friday with the vernal equinox, marking equal day/night.
• Japan celebrates Vernal Equinox Day; Mexico sees a serpent shadow at Chichen Itza.
• Days will lengthen in the north after March 20, 2026, at 10:46 a.m. EST.

Spring officially begins on Friday with the arrival of the vernal equinox, a significant astronomical event that occurs when day and night are nearly equal

in length. This equinox signals the start of spring in the Northern Hemisphere and fall in the Southern Hemisphere, with the sun positioned directly overhead at noon along the equator.

Historical Significance of the Equinox

Equinoxes have been celebrated globally for centuries. For instance, Japan observes Vernal Equinox Day as a public holiday. In Mexico, visitors flock to the Mayan site of Chichen Itza during the equinox to witness a unique shadow pattern resembling a serpent on the pyramid known as El Castillo.

Understanding the Equinox

As Earth orbits the sun, its axial tilt causes sunlight to be distributed unevenly across the planet. However, during the equinox, the tilt is such that both hemispheres receive equal sunlight, resulting in the sun rising almost directly in the east and setting almost directly in the west.

The term 'equinox' derives from Latin, meaning 'equal night,' as day and night are nearly equal in duration on this day. The Northern Hemisphere's spring equinox can occur between March 19 and 21, while the autumnal equinox happens between September 21 and 24.

The precise moment of the equinox occurs when the sun is directly above the equator. For 2026, this will happen on March 20 at 10:46 a.m. EST. Following this, days will gradually lengthen in the Northern Hemisphere until the summer solstice in June.

The Role of Solstices

Solstices mark the points in the year when Earth's tilt is most extreme in relation to the sun, resulting in significant disparities in sunlight received by each hemisphere. The Northern Hemisphere's summer solstice, which occurs between June 20 and 22, features the longest day and shortest night of the year, while the winter solstice, occurring between December 20 and 23, presents the shortest day and longest night.

Meteorological vs. Astronomical Seasons

Meteorological seasons differ from astronomical ones, as they are defined by temperature patterns rather than Earth's position in relation to the sun. Meteorologists categorize the year into three-month seasons: spring begins on March 1, summer on June 1, fall on September 1, and winter on December 1.