What is the Equinox in 2024?
In 2024, there are two equinoxes: the vernal (spring) equinox on March 19 and the autumnal (fall) equinox on September 22. These moments mark the Sun crossing the celestial equator and signal the start of spring in the Northern Hemisphere and autumn in the same hemisphere; the opposite seasons occur in the Southern Hemisphere.
An equinox is a celestial event that happens twice a year when the tilt of Earth's axis is such that the Sun appears to cross the celestial equator. On these days, the length of day and night is roughly equal, though exact daylight varies by latitude and weather. The dates are widely used to mark astronomical seasons and cultural seasonal transitions, and they help explain why daylight patterns shift through the year. This article outlines the 2024 dates and what they mean for seasons and daylight.
What is an equinox?
An equinox occurs when the tilt of the Earth's axis is neither tilted toward nor away from the Sun, causing the Sun to appear directly above the equator. There are two every year: the vernal (spring) equinox and the autumnal (fall) equinox. These events have long been used as markers for seasonal changes in many cultures.
Equinoxes in 2024
Two key dates for 2024 that define the seasonal transition are listed below.
- Vernal (spring) equinox: March 19, 2024
- Autumnal (fall) equinox: September 22, 2024
Keep in mind that the exact moment of the equinox depends on your time zone; civil calendars record the date, while the precise crossing time is defined in universal time (UTC) and occurs at a specific moment globally.
Time of day and time zones
Although the calendar dates are fixed, the precise moment of the Sun crossing the celestial equator happens at a specific time in UTC and will occur at different local times depending on where you are. This means that in some locations the equinox may feel like it occurs on one calendar day, while in others it could fall on the next day.
The vernal equinox in March marks the start of longer days in the Northern Hemisphere, while the autumnal equinox in September signals the start of shorter days. The Southern Hemisphere experiences the opposite seasonal shift in each case.
Implications for daylight and seasons
Here’s how the 2024 equinoxes affect daylight and seasons across hemispheres.
- Northern Hemisphere: Vernal equinox signals the return of longer daylight and the beginning of spring; Autumnal equinox marks the days growing shorter and the onset of autumn.
- Southern Hemisphere: The seasons are reversed relative to the Northern Hemisphere—autumnal equinox aligns with the start of spring there, and vernal equinox aligns with the start of autumn.
In practice, daylight lengths around the equinoxes are approximately equal between day and night, but latitude and atmospheric conditions cause variations. The equinoxes serve as useful benchmarks for calendars, agriculture, and cultural celebrations around the world.
Summary
The year 2024 features two key astronomical events called equinoxes: the vernal (spring) equinox on March 19 and the autumnal (fall) equinox on September 22. These moments mark the Sun crossing the celestial equator and indicate the transition of seasons, with daylight patterns shifting differently across the Northern and Southern Hemispheres. While the calendar dates are fixed, the exact moment in time depends on time zone and location.
