March Equinox 2024 Happens Tuesday, March 19, or Wednesday, March 20

Summary: The March 2024 equinox happens Tuesday, March 19, or Wednesday, March 20, as astronomical spring or fall opens, according to time zone and hemisphere.

graphic of astronomical and meteorological seasons in 2022 in the Northern Hemisphere during Earth's orbit around the sun; image credit NOAA Office of Education/Kaleigh Ballantine: via NOAA Office of Education

The March equinox in 2024 happens Tuesday, March 19, or Wednesday, March 20, according to Earth's time zones, and opens astronomical spring or autumn, according to location north or south of the equator.

The March equinox in 2024 takes place Tuesday, March 19, at 11:06 p.m. Eastern Daylight Time (EDT) in the Northern Hemisphere. The time of the Earth-wide event equates to Wednesday, March 20, at 03:06 Coordinated Universal Time (UTC), the Earth's primary time standard, according to the U.S. Naval Observatory, Astronomical Applications Department's "Earth Seasons -- Equinoxes and Solstices -- 2023-2026," published on the National Oceanic and Atmospheric Administration's (NOAA) National Weather Service website. The equinox occurs on Wednesday, March 20, for the 14 time zones that lie east of UTC. The equinox happens on Wednesday, March 20 for the first three time zones west of UTC and on Tuesday, March 19, for the last nine of the time zones west of UTC, according to "Time Zone Converter -- Time Difference Calculator (Classic)," published on the Time and Date website.

A positive UTC offset, symbolized as UTC+1 through UTC+14, designates time zones east of UTC. A negative UTC offset, expressed as UTC-1 through UTC-12, indicates time zones that lie west of UTC. Time zones east of UTC are ahead of UTC. Time zones west of UTC lag behind UTC.

The Northern Hemisphere and the Southern Hemisphere experience the March equinox as contrasting seasons. The March equinox opens astronomical spring the Northern Hemisphere but announces astronomical autumn in the Southern Hemisphere. The March equinox pairs annually with the September equinox, which flips the seasons for the two hemispheres. Accordingly, the September equinox functions as the opener of astronomical autumn in the Northern Hemisphere and as the announcer of astronomical spring in the Southern Hemisphere.

The year's two equinoxes pair with two solstices. The June solstice follows the March equinox. The December solstice succeeds the September equinox. The solstices correspond with astronomical summer and winter. The September solstice opens astronomical summer in the Northern Hemisphere and astronomical winter in the Southern Hemisphere. Contrastingly, the December solstice announces astronomical winter in the Northern Hemisphere and astronomical summer in the Southern Hemisphere.

The position of the Earth with respect to the sun determines Earth's astronomical seasons, as explained the National Oceanic and Atmospheric Administration's (NOAA) Office of Education in "Changing Seasons," published on the agency's website. "The Earth’s annual trip around the sun forms the basis for the astronomical calendar in which seasons are defined by two solstices and two equinoxes."

During Earth's annual orbit around the sun, its axis of rotation is tilted 23.5 degrees. The hemisphere favored by the axial tilt toward the sun experiences astronomical summer while the hemisphere disfavored by an away tilt undergoes astronomical winter.

The orientation of Earth's North Pole away or toward the sun determines astronomical summer and winter in the Northern Hemisphere. The northern tilt toward the sun, which occurs with the June solstice, initiates astronomical summer in the Northern Hemisphere. The northern polar tilt away from the sun, which happens with the December solstice, corresponds with astronomical winter in the Northern Hemisphere.

The away and toward tilts of the North Pole reverse astronomical summer and winter in the Southern Hemisphere. The northern polar tilt toward the sun during the June solstice signifies an away tilt at the South Pole. The northern polar away tilt during the December solstice effects a toward tilt at the South Pole.

Twice yearly the Earth's axis tilts neither away nor toward the sun. Earth's axis coordinates "in such a way" with Earth's orbit around the sun to suppress inclination, as explained by American science communicator and educator Deborah Byrd in "March equinox 2024: All you need to know about it," published March 19, 2023, on her EarthSky website. The year's two equinoxes represent the two absences of axial tilts. During the equinoxes, the solar path aligns with Earth's equator.

The March equinox in 2024 precedes the year's first solstice. June's solstice, opening northern summer and southern winter, is scheduled for Thursday, June 20, at 4:51 p.m. EDT and at 20:51 UTC. Three months later, the year's second equinox occurs Sunday, Sep. 22, at 8:44 a.m. EDT and 12:44 UTC. The December solstice occasions the year's last astronomical season with its occurrence Saturday, Dec. 21, at 4:21 a.m. Eastern Standard Time (EST) and at 09:21 UTC.

graphic of astronomical and meteorological seasons in 2022 in the Southern Hemisphere during Earth's orbit around the sun; image credit NOAA Office of Education/Kaleigh Ballantine: via NOAA Office of Education

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

graphic of astronomical and meteorological seasons in 2022 in the Northern Hemisphere during Earth's orbit around the sun; image credit NOAA Office of Education/Kaleigh Ballantine: via NOAA Office of Education @ https://www.noaa.gov/education/resource-collections/climate/changing-seasons

graphic of astronomical and meteorological seasons in 2022 in the Southern Hemisphere during Earth's orbit around the sun; image credit NOAA Office of Education/Kaleigh Ballantine: via NOAA Office of Education @ https://www.noaa.gov/education/resource-collections/climate/changing-seasons

For further information:

Byrd, Deborah. "March equinox 2024: All you need to know about it." EarthSky > Tonight > Astronomy Essentials. March 19, 2023.
Available @ https://earthsky.org/astronomy-essentials/everything-you-need-to-know-vernal-or-spring-equinox/

Davis, Lance D. "March Equinox Welcomes ‘Astronomical’ Spring." NOAA Blogs > Watch the Skies! March 18, 2022.
Available via NOAA Blogs @ https://blogs.nasa.gov/Watch_the_Skies/2022/03/

Marriner, Derdriu. "2017 Spring Equinox Happens Monday, March 20, in Northern Hemisphere." Earth and Space News. Wednesday, March 15, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/03/2017-spring-equinox-happens-monday.html

Marriner, Derdriu. "2019 Northern Hemisphere Spring Equinox Happens Wednesday, March 20." Earth and Space News. Wednesday, March 13, 2019.
Available @ https://earth-and-space-news.blogspot.com/2019/03/2019-northern-hemisphere-spring-equinox.html

Marriner, Derdriu. "American Samoa Has Autumn Equinox While United States Has Spring Equinox." Earth and Space News. Wednesday, March 1, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/03/american-samoa-has-autumn-equinox-while.html

Marriner, Derdriu. "First Point of Aries for Spring Equinox Actually Happens in Pisces." Earth and Space News. Wednesday, March 8, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/03/first-point-of-aries-for-spring-equinox.html

Marriner, Derdriu. "March 20 Equinox Opens 2020 Lineup of Two Equinoxes and Two Solstices." Earth and Space News. Wednesday, March 18, 2020.
Available @ https://earth-and-space-news.blogspot.com/2020/03/march-20-equinox-opens-2020-lineup-of.html

Marriner, Derdriu. "March Equinox Astronomically Opens Northern Spring and Southern Autumn." Earth and Space News. Wednesday, March 6, 2019.
Available @ https://earth-and-space-news.blogspot.com/2019/03/march-equinox-astronomically-opens.html

Marriner, Derdriu. "March Signals Autumn Equinox for American Samoa and Jarvis Island." Earth and Space News. Wednesday, March 20, 2019.
Available @ https://earth-and-space-news.blogspot.com/2019/03/march-signals-autumn-equinox-for.html

Marriner, Derdriu. "New Moon March 20, 2015, Totally Eclipses Sun and Welcomes Equinox." Earth and Space News. Thursday, March 19, 2015.
Available @ https://earth-and-space-news.blogspot.com/2015/03/new-moon-on-20th-march-2015-totally.html

Marshall Space Flight Center. "March Equinox Brings 2 Seasons: Spring, Autumn." NOAA Blogs > Watch the Skies! March 19, 2021.
Available via NOAA Blogs @ https://blogs.nasa.gov/Watch_the_Skies/2021/03/

NOAA Education. "Changing seasons." National Oceanic and Atmospheric Administration Education > Resources > Climate > Changing seasons.
Available via NOAA Education @ https://www.noaa.gov/education/resource-collections/climate/changing-seasons

U.S. Naval Observatory, Astronomical Applications Department. "Earth Seasons -- Equinoxes and Solstices -- 2023-2026." NOAA National Weather Service.
Available via NOAA National Weather Service @ https://www.weather.gov/media/ind/seasons.pdf