2019 June Solstice Happens Friday, June 21, or Saturday, June 22

Summary: The 2019 June solstice happens Friday, June 21, or Saturday, June 22, dates determined by local time zones with respect to Coordinated Universal Time.

The June solstice marks the sun’s zenith at noon over the Northern Hemisphere’s Tropic of Cancer; “A window on space shuttle Atlantis’ aft flight deck frames this scene featuring the Atlantic Ocean-Tropic of Cancer area south of Florida, including some of the 2700 islands that constitute the Bahamas;” Mission STS-135; July 9, 2011, 20 days after Tuesday, June 21, 2011, summer solstice: NASA, Public Domain, via NASA.

The 2019 June solstice happens Friday, June 21, or Saturday, June 22, with the two dates reflecting local time zone difference with respect to Coordinated Universal Time.

The 2019 June solstice takes place Friday, June 21, at 15:54 (3:54 p.m.), according to Coordinated Universal Time. Coordinated Universal Time (UTC) serves as the world’s primary time standard, with the world’s time zones expressed as negative or positive offsets from UTC.

Time zones that lag behind Coordinated Universal Time have negative offsets. Time zones with negative offsets lie west of the prime meridian (0 degrees longitude). The westernmost time zone lags 12 hours behind Coordinated Universal Time and has an offset of UTC-12.

Positive offsets reflect time zones that are ahead of Coordinated Universal Time. Time zones with positive offsets lie east of the prime meridian. The easternmost time zone registers as 14 hours ahead of Coordinated Universal Time and has an offset of UTC+14.

The 2019 June solstice takes place Saturday, June 22, in time zones that are more than eight hours ahead of Coordinated Universal Time. For example, Japan’s time zone, Japan Standard Time, has an offset of UTC+9. The 2019 June solstice occurs Saturday, June 22, at 12:54 a.m. JST. With an offset of UTC+14, the raised coral atoll of Kiritimati in the Republic of Kiribati’s northern Line Islands notes Saturday, June 22, at 5:54 a.m. LINT (Line Islands Time Zone) as the instant of the 2019 June solstice.

The 2019 June solstice takes place Friday, June 21, in time zones that are eight or less hours later than Coordinated Universal Time. With an offset of UTC+8, China’s only time zone, China Standard Time, experiences the instant of the 2019 solstice Friday, June 21, at 11:54 p.m. CST. In the Southern Hemisphere, with an offset of UTC+8, the state of Western Australia’s time zone, Australian Western Standard Time, also places the instant of the 2019 solstice Friday, June 21, at 11:54 p.m. AWST.

The June solstice occurs as the first of two annual solstices (Latin: sōlstitium, from sōl “sun” + sistō “stand still”). The year’s second solstice takes place in December.

The June and December solstices acknowledge the maximum tilt of Earth’s axis with respect to the sun. For the June solstice, the north polar terminus of Earth’s rotational axis tilts toward the sun while the south polar terminus tilts away from the sun. The June tilting accounts for greater receipt of direct rays of sunlight in the Northern Hemisphere than in the Southern Hemisphere.

The June solstice’s northern favoring opens astronomical summer in the Northern Hemisphere. The June solstice, contrastingly, signals astronomical winter in the Southern Hemisphere.

The December solstice reverses the favor. The instant of the December solstice represents the South Pole’s tilt toward the sun and the North Pole’s tilt away from the sun. At the time of the December solstice, more direct rays of sunlight arrive in the Southern Hemisphere than in the Northern Hemisphere.

The December solstice’s northern disfavoring opens astronomical winter in the Northern Hemisphere. Contrastingly, the solstice’s southern favoring opens astronomical spring in the Southern Hemisphere.

The June solstice marks the farthest northern point at which the sun appears directly overhead at noon. The reaching of the northernmost zenith occurs over the Northern Hemisphere’s Tropic of Cancer. The Tropic of Cancer encircles the globe near 23.5 degrees north latitude. Jerry T. Bonnell and Robert J. Nemiroff, American astrophysicists and co-creators of NASA’s APOD (Astronomy Picture of the Day) website, explain: “The latitude that defines the Tropic of Cancer corresponds to the tilt of planet Earth’s rotation axis with respect to its orbital plane.”

The December solstice references the sun’s noon reach of its vertical position over the Southern Hemisphere’s Tropic of Capricorn. As the Tropic of Cancer’s southern counterpart, the Tropic of Capricorn lies near 23.5 degrees south latitude.

The takeaway for the 2019 June solstice, which happens Friday, June 21, or Saturday, June 22, is that the astronomical event’s apparent, but not actual, two-day sprawl reflects local time zone differences.

The Northern Hemisphere experiences the June solstice as a summer solstice, with the sun overhead at the Tropic of Cancer: Alexander Novati/SciJinks, via USA.gov

Acknowledgment

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

Image credits:

The June solstice marks the sun’s zenith at noon over the Northern Hemisphere’s Tropic of Cancer; “A window on space shuttle Atlantis’ aft flight deck frames this scene featuring the Atlantic Ocean-Tropic of Cancer area south of Florida, including some of the 2700 islands that constitute the Bahamas;” Mission STS-135; July 9, 2011, 20 days after Tuesday, June 21, 2011, summer solstice: NASA, Public Domain, via NASA @ https://www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts135/multimedia/gallery/fd2ocean.html

The Northern Hemisphere experiences the June solstice as a summer solstice, with the sun overhead at the Tropic of Cancer: Alexander Novati/SciJinks, via USA.gov @ https://scijinks.gov/solstice/

For further information:

Case, Jack. “The Sun’s Declination, the Equinoxes and the Solstices.” Astro Navigation Demystified > Sun/Earth.
Available @ https://astronavigationdemystified.com/the-suns-declination-the-equinoxes-and-the-solstices/

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

Marriner, Derdriu. “2016 June Solstice Signals Summer Start But Also Begins Summer End.” Earth and Space News. Wednesday, June 15, 2016.
Available @ https://earth-and-space-news.blogspot.com/2016/06/2016-june-solstice-signals-summer-start.html

Marriner, Derdriu. “2017 June Solstice Happens Tuesday, June 20, or Wednesday, June 21.” Earth and Space News. Wednesday, June 21, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/06/2017-june-solstice-happens-tuesday-june.html

Marriner, Derdriu. “2018 June Solstice Happens Thursday, June 21, or Friday, June 22.” Earth and Space News. Wednesday, June 20, 2018.
Available @ https://earth-and-space-news.blogspot.com/2018/06/2018-june-solstice-happens-thursday.html

Marriner, Derdriu. “Northern Hemisphere 2017 Summer Solstice Happens Wednesday, June 21.” Earth and Space News. Wednesday, June 14, 2017.
Available @ https://earth-and-space-news.blogspot.com/2017/06/northern-hemisphere-2017-summer.html

Nemiroff, Robert J.; Jerry T. Bonnell. “Tropic of Cancer.” NASA Astronomy Picture of the Day. Aug. 2, 2013.
Available @ https://apod.nasa.gov/apod/ap130802.html

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

U.S.N.O. Astronomical Applications Department. “The Seasons and the Earth’s Orbit: Milankovitch Cycles.” U.S. Naval Observatory Astronomical Applications Department > Astronomical Information Center > Other Topics.
Available @ http://aa.usno.navy.mil/faq/docs/seasons_orbit.php

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Available @ http://aa.usno.navy.mil/faq/docs/rs_solstices.php

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