Sunday, March 19, 2017

Season of Spring Begins Early Monday Morning
This diagram shows the position of the Earth, in relation to the Sun, at the time of the Vernal Equinox, the official beginning of the Season of Spring, 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

The Vernal Equinox, which marks the beginning of the Season of Spring in Earth's Northern Hemisphere, occurs for 2017 on Monday Morning, March 20 at 6:29 a.m. Eastern Daylight Saving Time (EDT) / 10:29 Coordinated Universal Time (UTC).

In the Southern Hemisphere, this marks the astronomical beginning of the Season of Autumn.

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 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 degrees, 26 minutes, 13.4 seconds (23.43705 degrees) 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 (for Autumn or Fall), and about half-way between Winter and Summer (for Spring)] both planetary hemispheres receive an equal amount of solar radiation.

In Latin, Equinox, is defined as equal-night, the day when daylight and darkness are about equal in length. Such actual equal-night never occurs on the actual date of an Equinox on Earth. This is due to the fact that the Sun is so large, in relation to the Earth, and hence, the entire Sun does not appear at actual sunrise, only a portion of the Sun; it takes a few more minutes for the entire Sun to appear above the horizon. Also, due to the refractive nature of Earth's atmosphere, daylight can be seen before the Sun's disk can be observed.

The date of actual equal-night varies by a location's longitude and latitude. At the Earth's Equator, daytime is always longer than night. Hence, the Equator never has equal-night.

While the Vernal Equinox, the true beginning of the Season of Spring, occurs on March 20 at 6:29 a.m. EDT / 10:29 UTC, the literal Equinox for Spring, termed the Spring Equilux, actually occurs each year a few days earlier, usually around March 16 or 17 (depending on the specific location).

The Vernal Equinox is used in the solar calendars of Iran and Afghanistan as the beginning of their calendar year. In ancient times, the Vernal Equinox, then celebrated by the old style calendar on or near March 25, was also the beginning of the calendar year for many ancient civilizations.

An urban legend that has been making the rounds for decades 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!

This year, the Primary Moon Phase of Last Quarter for March occurs just a few hours after the Vernal Equinox: March 20 at 11:58 a.m. EDT / 15:58 UTC.

There is now an effort to have the day of the Vernal Equinox designated to commemorate the life of the first female astronomer, Hypatia of Alexandria, in ancient Egypt: Hypatia Day / Women in Science Day. Astronomical historian Ari Belenkiy, who finished an academic paper in 2016 on the life and death of Hypatia, has started an effort to have the day of the Vernal Equinox, March 20, designated by the Canadian Parliament as a day commemorating Hypatia's life. According to Professor Belenkiy, Hypatia's last days were dedicated to finding the exact time of the Vernal Equinox.

Hypatia was a Greek astronomer, mathematician, and philosopher, daughter of the mathematician Theon Alexandricus, who lived in Alexandria, Egypt during the late 4th and early 5th centuries. At that time Alexandria was part of the Eastern Roman Empire, which had a great rivalry with the Church of Rome. This led to deep divisions in Alexandria.

Due to the fog of time, there is much dispute regarding the events surrounding the death of Hypatia. According to the Church historian Socrates Scholasticus, a clique of Bishop Cyril's zealots killed Hypatia, due to a deep conflict between the Governor and Bishop of Alexandria. Hypatia's astronomical calculations regarding the date of Easter may have set the mob against her.

Although none of Hypatia's writings survive, she is reported to have made significant academic contributions in the fields of Astronomy and Mathematics.

The beginning of Spring also marks the beginning of the National Cherry Blossom Festival held each year in Washington, DC. This festival commemorates the 1912 gift of 3,000 cherry trees from the Mayor of Tokyo to the City of Washington. This year, the festival runs from March 15 through April 16.

Physicians have declared the first week of Spring as Medicine Cabinet Clean-Up Week. They urge families, as part of their annual Spring cleaning, to clean-out the medicine cabinet of old and expired pharmaceuticals which are no longer being used. This would prevent other family members from using these old drugs by accident, or the beginning of drug abuse.

Internet Links to Additional Information ---

Vernal Equinox: Link >>>

Season of Spring: Link >>>

Equinox: Link >>>

Earth's Seasons: Link >>>

Tilt of a planet's axis: Link >>>

Link 1 >>>
Link 2 >>>

Petition to designate March 20 to commemorate the life of Hypatia:
Link >>>

National Cherry Blossom Festival, Washington:
Link >>>

Medicine Cabinet Clean-Up Week: Link >>>

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.
             2017 March 19.

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