Tonight there will be a change in the seasons: the occurrence of the vernal equinox, which marks the official beginning of spring. Actually, it will be a very auspicious event. The earliest date when the equinox was observed nationwide is 128 years. More on this in a moment.
At the equinox, the Earth will have reached the point in its orbit where its axis is perpendicular to a line from the sun. So the sun will be directly above a specific point on the Earth’s equator, moving north. It is the place in the sky where the ecliptic and the celestial equator intersect.
It will also appear as if the sun is rising in the east and setting in the west. It is said that daylight and darkness are directly proportional and the sun’s rays spread to the poles. The sun is above the horizon for half the day and below it for the other half; but this statement ignores the effect of the Earth’s atmosphere, which bends rays of sunlight (called refraction) around the curvature of the Earth when the sun is near the horizon. But due to this bending of the sun’s rays, the solar disk is always seen slightly higher than above the horizon.
Relating to: What is the equinox?
In fact, when you see the sun appear on the horizon, what you are looking at is a optical illusion; At that moment the sun is actually under Horizon. So we have a few extra minutes of daylight at the beginning of the day and a few extra minutes of daylight at the end of the day.
The so-called equality of night and day gives us the Latin name “equinox”, which actually means “equality of night”. However, in reality, the day is longer than the night at the equinox, thanks to our atmosphere. For example, at the latitude of New York, day and night are roughly equal on St. Patrick’s Day, March 17, a few days before the equinox.
The sun is out near New Guinea
Astronomers can calculate the moment of the vernal equinox to the nearest second. This year it will take place on Tuesday, March 19th at 11:06:20 PM EDT. At that moment, the sun will appear directly overhead over the equatorial Pacific Ocean, northeast of West Papua, New Guinea, and about 63 miles (101 km) south of Mapia Atoll, historically known as the Free Will Islands or San David. In the coming days, direct rays from the Sun will continue to move north of the equator and accordingly, the duration of daylight in the Northern Hemisphere will be prolonged.
Why so early?
As previously mentioned, this will be the earliest time the vernal equinox will occur in the contiguous United States in 128 years. There are two specific reasons for this:
1) The four-year intervention of a leap year usually causes a slight change in history.
2) Daylight saving time (DST)
When a leap year takes us back one day
First of all, the fact that 2024 is a leap year Negative The reason for the early arrival of this year’s equinox. Rather, the one we observed in 2000 is a leap year.
Let’s look at the dates and times of the equinoxes up to the year 2000. Note that the equinox occurs about 6 hours (or a quarter of a day) later on the calendar each year:
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1996 March 20 03:03 EST
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1997 March 20 08:54 EST
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March 20, 1998 14:54 EST
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1999 March 20 20:46 EST
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March 20, 2000 02:35 EST*
In 46 BC, Sosigenes, Julius Caesar’s advisor astronomer, knew from Egyptian experience that the solar year was approximately 365.25 days long. Thus, to account for the remaining quarter of a day, an extra day – a leap day – was added to the calendar every four years. Unfortunately the new Julian calendar was 11 minutes 14 seconds LONG than the actual solar year. By 1582—due to overcompensation for observing too many leap years—the calendar was out of sync with the solar year by a total of 10 days.
That’s when Pope XIII. Gregory stepped in and, with the advice of his own astronomer Christopher Clavius (1538-1612), created our current “Gregorian” calendar. First, to wrap things up, ten days after October 4, 1582 were skipped, making the next day October 15. Later, to make a closer match to the length of the solar year, i.e. centennial years in the old Julian calendar, leap years became, and were not, years. The exception was century years, which were equally divisible by 400. Therefore, 1700, 1800 and 1900 were not leap years.
However, the year 2000 was a century year evenly divisible by 400, so it was considered a leap year. If we skipped the leap year in 2000 (as in 1900), then the equinox would begin in March. 21 At 2:35 EST.
That’s why we put an asterisk
next to this history. So in 2000, February had an extra day, so the equinox date changed. fell behind one day
Until March 20.
Daylight saving time in the East postponed to March 19 equinox And because the excess added to 365 is not exactly a quarter (.2500) of the day, but slightly less than a quarter (.2422), the equinox occurs. 47 minutes ago
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(on average) every four years:
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March 20, 2000 02:35 EST
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2004 March 20 01:48 EST
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March 20, 2008 01:48 EDT*
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March 20, 2012 01:14 EDT
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March 20, 2016 12:30 EDT
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March 19, 2020 23:49 EDT
March 19, 2024 23:06 EDT
The asterisk indicates that we have been observing Daylight Saving Time since the beginning of March… a practice that began in 2007. In 2000, only those in the Pacific Time Zone observed the equinox on March 19. In 2004, 2008 and 2012, spring appeared to arrive on the 19th in the Pacific and Mountain Time Zones.
In 2016, those in the Central Time Zone celebrated the arrival of spring on March 19. If we were still on the old system (DST didn’t start until early April), we would be on standard time in 2016, and Easterners would observe the equinox on the 19th (at 11:30 p.m.)… but daylight time delayed that by another four years. Finally, in 2020, spring came from coast to coast on March 19, and it will come again in 2024.
And as a point of record: In 1896, the vernal equinox occurred on March 19 at 9:29 pm EST.
Astronomical and meteorological spring
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To tell the truth, there are actually two springs: the astronomical spring and the meteorological spring. Astronomical Spring is measured by the vernal equinox, but this is only a blip in the great human-created flow of time; a stellar milestone. It’s about as accurate as a ticking clock, but the timing of the seasons is about right. Meteorological
It is said that spring begins on March 1 and continues until the end of May. But in reality, meteorological spring ignores the clock and the calendar, makes its own rules and creates a festival of song and flowers in its own time.
Crocuses, early robins and other springtime events pay no attention to the grisly details that mark the astronomical arrival of the vernal equinox. They all have their own ways of knowing when spring will truly begin. Joe Rao is an instructor and visiting professor in New YorkHayden Planetarium . writes about astronomyNatural History magazine , Farmer’s Almanac