The Earth at the start of the 4 (astronomical) seasons as seen from the north and ignoring the atmosphere (no clouds, no twilight). Front left: Summer Solstice for the Northern Hemisphere. Rear right: Summer Solstice for the Southern Hemisphere. (Image Source: Wikipedia.org )
By Glenn A. Walsh
Reporting for SpaceWatchtower
The
moment of the Summer Solstice, heralded as the beginning of the season
of Summer in Earth's Northern Hemisphere (and the season of Winter in
the Southern Hemisphere), will be early Saturday Morning, 2014 June 21, at 6:51 a.m. Eastern Daylight Saving Time (EDT) / 10:51 Coordinated
Universal Time (UTC). A little more than a week earlier came the Full Moon on Friday the 13th.
In etymology, the word solstice comes from the Latin terms sol (Sun) and sistere
(to stand still). In ancient times, astronomers / astrologers / priests
recognized that on one day of the year (in the Northern Hemisphere,
near the day we now call June 21), the Sun would appear
to reach its highest point in the sky for the year. The motion of the
Sun's apparent path in the sky (what is known astronomically, today, as
the Sun's declination) would cease on this day, before reversing direction.
Today,
we know that, while the Sun does have motions, it is actually the
motion of the Earth, tilted on its axis 23.44 degrees while revolving
around the Sun, that causes the Earth's seasons. Hence, as the Earth
arrives at the point in its orbit around the Sun, when the north polar
axis is most directly inclined toward the Sun, this marks the Summer Solstice
in the Northern Hemisphere.
Alternately, the Winter Solstice, in the Northern Hemisphere, occurs when the Earth reaches the point in its orbit when the north polar axis is most directly inclined away the Sun. And, conversely, at this time Summer begins in the planet's Southern Hemisphere.
Although the Summer months in the Northern Hemisphere are known for the year's warmest weather, the Earth is actually at the point in its orbit farthest from the Sun (astronomically known as the point of aphelion) around July 5; the Earth's closest approach to the Sun (perihelion) each year is around January 2. Solar radiation, and hence the heat from the Sun, depends on the length of daylight and the angle of the Sun above the horizon. The tilt of the planet's axis toward the Sun determines the additional and more direct solar radiation received by a planet's northern or southern hemisphere, and hence, the warmer season of the respective hemisphere.
Alternately, the Winter Solstice, in the Northern Hemisphere, occurs when the Earth reaches the point in its orbit when the north polar axis is most directly inclined away the Sun. And, conversely, at this time Summer begins in the planet's Southern Hemisphere.
Although the Summer months in the Northern Hemisphere are known for the year's warmest weather, the Earth is actually at the point in its orbit farthest from the Sun (astronomically known as the point of aphelion) around July 5; the Earth's closest approach to the Sun (perihelion) each year is around January 2. Solar radiation, and hence the heat from the Sun, depends on the length of daylight and the angle of the Sun above the horizon. The tilt of the planet's axis toward the Sun determines the additional and more direct solar radiation received by a planet's northern or southern hemisphere, and hence, the warmer season of the respective hemisphere.
The Vernal Equinox, when the season of Spring begins in the Northern Hemisphere, occurs between the Winter and Summer Solstices when the Earth reaches the point in its orbit around the Sun when the Earth's axis is inclined neither toward nor away from the Sun. Likewise, when the Earth reaches the point in its orbit around the Sun when the Earth's axis is inclined neither toward nor away from the Sun, between the Summer and Winter Solstices, this is known as the Autumnal Equinox. And, half-way between the beginning points of each season are Cross-Quarter Days, related to the traditional holidays of Groundhog Day, May Day, Lammas Day (traditionally, first harvest festival of the year on August 1), and Halloween Day.
In
ancient times, the Summer Solstice was known as Midsummer Day, in
earlier calendars celebrated around June 24. Such early European
celebrations were pre-Christian in origin. Many will associate this
ancient holiday with the famous William Shakespeare play, A Midsummer Night's Dream. Some speculate that the play was written for the Queen of England, to celebrate the Feast Day of Saint John.
As with the Roman Catholic Church's decision to christianize the pagan Winter Solstice festivals with the introduction of Christmas Day on December 25, the Church began to associate the Midsummer festivals with the Nativity of Saint John the Baptist on June 24. In the Bible, the Gospel of Saint Luke implies that John was born six months before the birth of Jesus, although no specific birth dates are provided.
As with the Roman Catholic Church's decision to christianize the pagan Winter Solstice festivals with the introduction of Christmas Day on December 25, the Church began to associate the Midsummer festivals with the Nativity of Saint John the Baptist on June 24. In the Bible, the Gospel of Saint Luke implies that John was born six months before the birth of Jesus, although no specific birth dates are provided.
More on the Summer Solstice -
Link 1 >>> http://scienceworld.wolfram.com/astronomy/SummerSolstice.html
Link 2 >>> http://en.wikipedia.org/wiki/Summer_solstice
More on the Season of Summer: Link >>> http://en.wikipedia.org/wiki/Summer
More on the history of Midsummer: Link >>> http://en.wikipedia.org/wiki/Midsummer
Summer "Solstice Day" Annual Free-of-Charge Day, 1985 to 1991, at Pittsburgh's original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl Science Center):
Link >>> http://buhlplanetarium2.tripod.com/Buhlexhibits.htm#solstice
Related Blog Post ---
Friday the 13th Full Moon ! (2014 June 12):
Link >>> http://spacewatchtower.blogspot.com/2014/06/friday-13th-full-moon.html
Special Thanks: Eric G. Canali, former Floor Manager of Pittsburgh's original Buhl Planetarium and Institute of Popular Science and Founder of the South Hills Backyard Astronomers amateur astronomy club.
Source: Glenn A. Walsh, Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
2014: 75th Year of Pittsburgh's Buhl Planetarium
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gaw
Glenn A. Walsh, Project Director,
Friends of the Zeiss < http://buhlplanetarium.tripod.com/fotz/ >
Electronic Mail - < gawalsh@planetarium.cc >
About the SpaceWatchtower Editor / Author: < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
SpaceWatchtower Blog: < http://spacewatchtower.blogspot.com/ >
Also see: South Hills Backyard Astronomers Blog: < http://shbastronomers.blogspot.com/ >
Barnestormin: Writing, Essays, Pgh. News, & More: < http://www.barnestormin.blogspot.com/ >
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Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
< http://www.planetarium.
* Adler Planetarium, Chicago:
< http://adlerplanetarium.
* Astronomer, Educator, Optician John A. Brashear:
< http://johnbrashear.tripod.com >
* Andrew Carnegie & Carnegie Libraries:
< http://www.andrewcarnegie.
* Civil War Museum of Andrew Carnegie Free Library:
< http://garespypost.tripod.com >
* Duquesne Incline cable-car railway, Pittsburgh:
< http://inclinedplane.tripod.
* Public Transit:
< http://andrewcarnegie2.tripod.
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