Despite Winter-Type Storms, Spring Begins Today!

This diagram shows the position of the Earth, in relation to the Sun, at the time of the Vernal Equinox at the official beginning of the season of Spring in the Earth's Northern Hemisphere (Autumn in Earth's Southern Henmisphere), as well as the other solstices and equinox of the year.
(Graphic Source: ©1999, 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; permission granted for only non-profit use with credit to author.)

By Glenn A. Walsh

Reporting for SpaceWatchtower

Despite snow storms threatening the American Northeast, including the fourth Nor-Easter in a month about to hit the East Coast, Spring begins today at the moment of the Vernal Equinox in Earth's Northern Hemisphere. In the Southern Hemisphere, this marks the astronomical beginning of the season of Autumn.

The posting of this blog-post comes at the moment of the Vernal Equinox: 12:15 p.m. Eastern Daylight Saving Time (EDT) / 16:15 Coordinated Universal Time (UTC) on Tuesday Afternoon, 2018 March 20.

As the diagram at the beginning of this blog-post demonstrates, on the day of Equinox the Sun appears directly overhead at local Noon on the Equator. At the moment of Equinox, the Northern and Southern Hemispheres of Earth are illuminated equally. And, the time of Equinox is the only time when the Earth Terminator (dividing line on Earth between daylight and darkness) is perpendicular to the Equator.

This, and the reason for seasons on Earth in the first place, is due to the fact that Earth rotates on its axis, which is tilted at a 23.439281-degree angle from the plane of the Earth's orbit around the Sun. As the Earth revolves around the Sun, this axial tilt causes one hemisphere of the planet to receive more direct solar radiation during that hemisphere's season of Summer and much less direct solar radiation a half-year later during that hemisphere's season of Winter. As mentioned, during an Equinox (about half-way between Summer and Winter, and about half-way between Winter and Summer) both planetary hemispheres receive an equal amount of solar radiation.

Although "Equinox" in Latin means equal-night, the day of the Equinox does not actually have an equal amount of daylight and nightfall, as it appears on the Earth's surface. If the Sun was just a pin-point of light in our sky, as all other stars appear, day and night would be equal.

But, because the Sun is a disk, part of the Sun has risen above the horizon before the center of the Sun (which would be the pin-point of light); so there are extra moments of light on the Equinox. Likewise, part of the Sun is still visible, after the center of the Sun has set.

Additionally, the refraction of sunlight by our atmosphere causes sunlight to appear above the horizon, before sunrise and after sunset.

March 16 marked the Equilux ("equal-light"), the actual day with equal hours and minutes of the Sun above the horizon, and equal hours and minutes of the Sun below the horizon. The Equilux occurs twice each year, approximately 3-to-4 days before the Vernal Equinox and 3-to-4 days after the Autumnal Equinox (September 25).

An urban legend that has been making the rounds for decades, now exacerbated by the Internet and Social Media, has it that eggs can be stood on their ends only during an Equinox, whether the Vernal Equinox in the Spring or the Autumnal Equinox in the Fall. This is completely false!

Depending greatly on the size and shape of the particular egg, eggs can be stood on their ends any day of the year! Astronomy has nothing to do with whether an egg can stand on its end. If an egg can stand on its end on the Equinox (and, due to the shape and size of some eggs, this is not even possible), it can stand the same way any other day of the year.

In the last few years, with the help of the Internet and Social Media, another urban legend has become prevalent. Now it is claimed that brooms can stand, on their own, on their bristles, only on an Equinox day. This is also false! Again, as with eggs, if a broom can stand on its bristles by itself (this usually only works with newer brooms, with more even bristles) on an Equinox, it can do so any day of the year!

In ancient times, the Vernal Equinox was considered the beginning of the new calendar year. This was when most of Western Civilization used the Julian Calendar, and the Vernal Equinox occurred on March 25, later observed by Christians as the Feast of the Annunciation (observed nine full months before Christmas Day). As part of the Gregorian Calendar reform, in October of 1582, Pope Gregory XIII chose the Feast of the Circumcision of Christ (January 1) as the beginning of the New Year in the Roman Catholic Church's Liturgical Year.

The Vernal Equinox continues to be considered the beginning of the New Year, or an important holy day, in several other places on Earth ---

Beginning of New Year (using the Solar Calendar) - Nowruz: Afghanistan and Iran / Persia

Also a Holy Day for adherents to the Zoroastrian Religion and Baha'i Naw-Ruz, one of nine holy days of the Bahá'í Faith.

NASA and the European Space Agency (ESA) observe Sun-Earth Day on or near the Vernal Equinox. This is a joint educational program started in 2000, to popularize the knowledge about the Sun, and the way it influences life on Earth, among students and the public. This is part of Solar Week, which is the calendar week that includes the Vernal Equinox.

The first week of Spring, beginning with the Vernal Equinox, has been declared by physicians as Medicine Cabinet Clean-Up Week. To avoid prescription drug abuse, particularly important at this time of the opioid crisis, physicians encourage everyone to get rid of unused and no-longer-needed medications and other drugs, which may have lingered in the household, as part of an annual Spring cleaning. Several states have prescription drug take-back locations, where these drugs can be dropped-off.

The week of the Vernal Equinox is the also the beginning of the National Cherry Blossom Festival held each year in Washington, DC, which began on March 17. This festival commemorates the 1912 gift of 3,000 cherry trees from the Mayor of Tokyo to the City of Washington. The festival runs through April 15 this year. More information on the festival:

Link >>> http://www.nationalcherryblossomfestival.org/?id=404

More on the Vernal Equinox: Link >>> http://scienceworld.wolfram.com/astronomy/VernalEquinox.html

More on the Season of Spring: Link >>> http://en.wikipedia.org/wiki/Spring_%28season%29

More on an Equinox: Link >>> http://en.wikipedia.org/wiki/Equinox

More on Earth's Seasons: Link >>> http://en.wikipedia.org/wiki/Season

More on the tilt of a planet's axis: Link >>> http://en.wikipedia.org/wiki/Axial_tilt

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.
             2018 March 20.

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