2019 Northern Hemisphere Spring Equinox Happens Wednesday, March 20

Summary: The 2019 Northern Hemisphere spring equinox happens Wednesday, March 20, at 21:58 Coordinated Universal Time (5:58 p.m. Eastern Daylight Time).

view of March 20, 2011, equinox from space; SEVIRI (Spinning Enchanced Visible and Infrared Imager) on EUMETSAT’s Meteosat-9 satellite: NASA Earth Observatory via NASA GSFC (Goddard Space Flight Center) Scientific Visualization Studio

The 2019 Northern Hemisphere spring equinox happens Wednesday, March 20, at 21:58 Coordinated Universal Time (5:58 p.m. Eastern Daylight Time), according to the U.S. Naval Observatory Astronomical Applications Department.

The Northern Hemisphere’s spring equinox occurs annually in March and pairs with the northern autumn equinox, which occurs in September. The U.S. Naval Observatory’s Astronomical Applications Department website explains the significance of the annual equinoxes (Latin: aequus, “equal” + nox, “night”): “On the day of an equinox, the geometric center of the Sun’s disk crosses the equator, and this point is above the horizon for 12 hours everywhere on the Earth.”

Point Udall, St. Croix, United States Virgin Islands (USVI), claims the easternmost point of all U.S. territory, by direction of travel. Point Udall’s geographic coordinates are 17 degrees 45 minutes 19 minutes north latitude and 64 degrees 33 minutes 54 seconds west longitude. Officially known as the Virgin Islands of the United States, the unincorporated and organized U.S. territory in the Caribbean Sea joins the Commonwealth of Puerto Rico in observing Atlantic Standard Time (AST) year-round.

AST’s UTC (Coordinated Universal Time) offset, UTC-4, reflects the time zone’s lag of four hours behind UTC. The 2019 Northern Hemisphere spring equinox takes place Wednesday, March 20, at 5:58 p.m. AST.

Pochnoi Point, Semisopochnoi Island, in Alaska’s Aleutian Islands, claims the easternmost longitudinal point of all U.S. territory. Pochnoi Point lies at 51 degrees 57 minutes 42 degrees north latitude and 179 degrees 46 minutes 23 seconds east longitude. The portion of Alaska’s Aleutian Islands lying west of 169 degrees 30 minutes west longitude observes Hawaii-Aleutian Time. The 2019 spring equinox starts at 12:58 p.m. HDT (also abbreviated as HADT).

Point Udall, Orote Peninsula, Guam, claims the westernmost point of all U.S. territory, by direction of travel. The geographic coordinates for Point Udall, also known as Orote Point, are 13 degrees 26 minutes 51 seconds north latitude and 144 degrees 37 minutes 5.5 seconds east longitude. The unincorporated and organized U.S. Territory of Guam observes Chamorro Standard Time year-round. The 2019 spring equinox begins Thursday, March 21, at 07:58 a.m. ChST.

Amatignak Island in Alaska’s Aleutian Islands claims the westernmost longitudinal point of all U.S. territory. Amatignak Island lies at 51 degrees 16 minutes 7 seconds north latitude and 179 degrees 8 minutes 55 seconds west longitude. Falling with the Hawaii-Aleutian time zone, Amatignak Island experiences the instant of the 2019 spring equinox at 12:58 p.m. HDT.

Six time zones convert the instant of the 2019 Northern Hemisphere spring equinox to local time in the continental United States. The continental United States encompasses the District of Columbia (Washington, D.C.); the 48 contiguous states, known as the lower 48; Alaska.

The continental United States mostly observes standard time annually for eight months and daylight saving time for four months. The switch to daylight saving time happens well before the Northern Hemisphere’s spring equinox occurs. Daylight saving time takes effect at 2 a.m. on the second Sunday in March.

Three of the four time zones observed in the lower 48 switch to daylight saving time prior to the March equinox. The spring equinox commences at 5:58 p.m. EDT, 4:58 p.m. Central Daylight Time, 3:58 p.m. Mountain Daylight Time and 2:58 p.m. Pacific Daylight Time.

Most of Arizona remains on Mountain Standard Time throughout the year. The 2019 spring equinox begins at 2:58 p.m. MST. On Navajo tribal lands, where daylight saving time is observed, the 2019 spring equinox starts at 3:58 MDT.

Alaska claims uniqueness as the only U.S. state that is part of the continental United States but not part of the contiguous United States. The northernmost of the continental U.S. states also likens to 12 other states in splits between time zones. In addition to Alaska, time zone splits take place in Florida, Idaho, Indiana, Kansas, Kentucky, Michigan, Nebraska, North Dakota, Oregon, South Dakota, Tennessee and Texas.

Alaska observes daylight saving time in both of the state’s time zones. Alaska Daylight Time places the instant of the 2019 spring equinox at 1:58 p.m. for mainland Alaska and most of Alaska’s Aleutian Islands. The 2019 spring equinox begins at 12:58 p.m. HDT for the portion of Alaska’s Aleutian Islands to the west of 169 degrees 30 minutes west longitude.

The Hawaiian Islands observe standard time year-round. The 2019 spring equinox occurs at 11:58 a.m., according to HAST.

The takeaway for the 2019 Northern Hemisphere spring equinox, which happens Wednesday, March 20, at 21:58 Coordinated Universal Time (5:58 p.m. Eastern Daylight Time), is that the annual astronomical event occurs during daylight saving time (DST) for most of the continental United States but during standard time for most of Arizona as well as for Hawaii and U.S. territories.

Map of the standard time zones of the 50 U.S. states indicates 13 split time zone states (Alaska, Florida, Idaho, Indiana, Kansas, Kentucky, Michigan, Nebraska, North Dakota, Oregon, South Dakota, Tennessee, Texas) one standard time zone only state (Hawaii) and one mostly standard time zone state (Arizona); The National Atlas of the United States of America: U.S. Department of the Interior-U.S. Geological Survey, via U.S. Naval Observatory Astronomical Applications Department

Acknowledgment

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

Image credits:

view of March 20, 2011, equinox from space; SEVIRI (Spinning Enchanced Visible and Infrared Imager) on EUMETSAT’s (European Organisation for the Exploitation of Meteorological Satellites) Meteosat-9 satellite: NASA Earth Observatory via NASA GSFC (Goddard Space Flight Center) Scientific Visualization Studio @ https://svs.gsfc.nasa.gov/11353

Map of the standard time zones of the 50 U.S. states indicates 13 split time zone states (Alaska, Florida, Idaho, Indiana, Kansas, Kentucky, Michigan, Nebraska, North Dakota, Oregon, South Dakota, Tennessee, Texas) one standard time zone only state (Hawaii) and one mostly standard time zone state (Arizona); The National Atlas of the United States of America: U.S. Department of the Interior-U.S. Geological Survey, via U.S. Naval Observatory Astronomical Applications Department @ https://commons.wikimedia.org/wiki/File:NGC_5634_Hubble_WikiSky.jpg

For further information:

Espenak, Fred. “Solstices and Equinoxes: 2001 to 2100 Greenwich Mean Time.” AstroPixels > Ephemeris.
Available @ http://www.astropixels.com/ephemeris/soleq2001.html

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. “2018 Northern Hemisphere Spring Equinox Happens Tuesday, March 20.” Earth and Space News. Wednesday, March 14, 2018.
Available @ https://earth-and-space-news.blogspot.com/2018/03/2018-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 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

Time And Date. “Time Zones in the United States.” Time And Date > Time Zones > World > United States.
Available @ https://www.timeanddate.com/time/zone/usa

U.S.N.O. Astronomical Applications Department. “Comparative Lengths of Days and Nights.” U.S. Naval Observatory Astronomical Applications Department > Information Center > Phenomena of the Sun and Moon > Lengths of Longest and Shortest Days.
Available @ http://aa.usno.navy.mil/faq/docs/longest_day.php

U.S.N.O. Astronomical Applications Department. “Daylight Time.” U.S. Naval Observatory Astronomical Applications Department > Information Center > Time > When Does Daylight Time Begin and End?
Available @ http://aa.usno.navy.mil/faq/docs/daylight_time.php

U.S.N.O. Astronomical Applications Department. “Earth’s Seasons and Apsides.” U.S. Naval Observatory Astronomical Applications Department > Data Services > Equinoxes, Solstices, Perihelion, and Aphelion.
Available @ http://aa.usno.navy.mil/data/docs/EarthSeasons.php

U.S.N.O. Astronomical Applications Department. “Equinox.” U.S. Naval Observatory Astronomical Applications Department > Information Center > Terms Used on This Website > The Astronomical Almanac Online.
Available @ http://asa.usno.navy.mil/SecM/Glossary.html#_E

U.S.N.O. Astronomical Applications Department. “Equinoxes.” U.S. Naval Observatory Astronomical Applications Department > Information Center > Phenomena of the Sun and Moon > Length of Day and Night at the Equinoxes.
Available @ http://aa.usno.navy.mil/faq/docs/equinoxes.php

U.S.N.O. Astronomical Applications Department. “Universal Time.” U.S. Naval Observatory Astronomical Applications Department > Information Center > Time > Universal Time and Greenwich Mean Time.
Available @ http://aa.usno.navy.mil/faq/docs/UT.php

U.S.N.O. Astronomical Applications Department. “U.S. Time Zones.” U.S. Naval Observatory Astronomical Applications Department > Information Center > Time > What Are the U.S. Time Zones?
Available @ http://aa.usno.navy.mil/faq/docs/us_tzones.php