[Updated March 19, 2016 at 15:00] The Spring Equinox 2016, it is for this week- end! This moment – which marks the transition from winter to spring – corresponds to a time of year when the sun crosses the equatorial plane of the earth. The star was then at the zenith of Ecuador. The best known of this astronomical phenomenon consequence is that the days and nights have the same approximate length everywhere on Earth , in both hemispheres, south and north. For our part, the days get longer and we are halfway between the short days of December and the long days of June. The equinox occurs twice a year: between 19 and 21 March (vernal or spring equinox) and between 22 and 23 September (autumnal equinox)
In 2016. , spring officially starts this Sunday 20 March at exactly 5:30 . But how was fixed that day of spring? Why spring, the first day is generally the 21 March in the collective imagination, arrives a day early this year? What is the difference between the astronomical spring and the spring weather? But what are the traditions and cults associated with the spring equinox? It is these questions that we intend to answer in this special page.
In 2016, the spring thus starts officially March 20. A date and even time ( 5:30 ET 11 seconds precisely) that spring 2016 one of the earliest history of the country. How to explain that the first day of spring falls so early in the year? Note that the exact time of the equinox – that is to say the time the equatorial plane and the trajectory of the Earth coincide – is calculated for each year by astronomers and mathematicians. A calculation made necessary by the gap between our calendar and time system and the movements of the stars. First, the Earth’s orbit is not perfectly circular, so that in relation to its position on this orbit, the Earth may be more or less close to the sun (between 147 million kilometers and minimum up to 152 million kilometers). That inevitably makes the durations of each very irregular season
Another explanation. Earth does not exactly 365 days to circle the sun. In this our Gregorian calendar, established in the sixteenth century, is far too simplistic. It is indeed 365.2422 days exactly (365 days, 5 hours and 46 minutes) so that we have come full circle to the star! We are already obliged to add from time to time on February 29 (in leap years) to correct in part (and only partially) offset this. So the man has not quite managed to adapt his schedule to the law of the seasons. When establishing the Julian calendar by Caesar in 45 BC, the spring equinox was set for March 25, based on inaccurate observations of the time. But the absence of February 29 in this ancient calendar eventually move that date up to March 11 in the sixteenth century … It is only when establishing the Gregorian calendar (the one we use today) in 1582, approaching a date of March 21 has been selected.
on the astronomical point of view, spring begins at the vernal equinox, which may take place between 19 and March 21. In the coming years, it will be mainly on 20 March. This was also the case in 2015, the spring equinox was then held on 20 March, 22:45 9 seconds Universal Time (or 11:45 p.m. ET nine seconds at the Paris time). It was not until 2044 years for the equinox occurs on 19 March. As for the summer solstice, it will be for the next 21 June 2016. What makes the spring lasts about three months.
But this definition of official spring is not universal. In meteorology, for example considering that spring begins the 1 st in March and ended on 31 May: in this discipline, we characterized the spring as a period of warming temperatures and (in our latitudes ) the length of the day. It is also one of the hardest seasons to analyze in this discipline.
In this table, find exact dates of the equinoxes until 2020 . Schedules are established “Universal Time” (T.U.). To find the time of the equinox in the time zone of Paris, add one hour to the spring and two hours for the fall. This offset difference is due to the time change system applied in France and Europe:
| Year | Vernal equinox | Equinoxe fall |
|---|---|---|
| 2015 | March 20 / 10:45 p.m. | September 23 / 8:20 |
| 2016 | March 20 / 4:30 | September 22 / 2:21 p.m. |
| 2017 | March 20 / 10:28 | September 22 / 8:02 p.m. |
| 2018 | March 20 / 4:15 p.m. | September 23 / 1:54 |
| 2019 | 20 March / 9:58 p.m. | September 23 / 7:50 |
| 2020 | March 20 / 3:50 | September 22 / 1:31 p.m. |
the word equinox comes from the Latin ” aequinoctium “(” equal night “) as the most visible phenomenon for humans is that the day length becomes identical to that of the night . The origins of this phenomenon is related to the geometry. The axis of rotation of the Earth is naturally inclined 23.4 ° relative to the plane of its orbit. In other words, our planet “looks” from the plane in which it orbits the Sun (see diagram below). The star illuminates the so differently at different times of the year. This explains why the days get longer or shorter between summer and winter. This gives rise to the seasons, due to the warming or cooling of the air masses and oceans by time spent each day under the rays of the sun. The distance between the sun and Earth has no direct link with the temperature. Note for example that the Earth reaches the closest point to the sun (perihelion) on January 3 that is the heart of our winter.
two equinoxes are the two moments the year in which the axis of rotation of the Earth itself and the axis of rotation of the Earth around the Sun exact match. On our planet, at the equinox, our star appears pile east at dawn to disappear just west. The sun is at its zenith exactly above the equator. And above all, day and night are of equal duration of 12 hours. In spring this continuous sunshine duration of rising to the equinox to 16 hours at the end of June (in France). These data however vary slightly since the shape of the Earth is not perfectly regular and the atmosphere slightly away sunlight. Thus, in Paris on 20 March, the sun will rise at 6:52 and sets at 7:03 p.m.. Day length is very slightly greater than 12 hours. This is the time of the equinoxes as day length increases / decreases faster in our latitudes.
The equinox is thus opposed to the solstices Summer and winter: they are when day length is the longest, around June 21, or shorter, around December 21. Dates are obviously reversed in the Southern Hemisphere. All these events also originate shift of 23 ° between the axis of rotation of the earth and of its orbit . Without this shift, we would know not simply the seasons …
In 2015, the spring equinox was marked by a spectacular natural phenomenon: “tide of the century” . It occurs on average every 18 years, according to the Hydrographic and Oceanographic Service of the Navy (SHOM). coefficients reached 119 Saturday, March 21 on the coasts of the Atlantic and the North Sea. The tidal range, that is to say the difference in height between measured water levels tide and a consecutive low sea, reached 14.15 meters in the Bay of Mont Saint-Michel.
In general, the tides are caused by the gravitational pull of the Sun and the Moon. equinox period , the race the sun passes over the equator: it is at this time that its action on the tides is greatest. The coefficients are generally stronger in September and March that the rest of the year. Our satellite is found in the same axis as that of the sun. The attraction of the two stars is added (known as “ syzygy “, when the Sun, Moon and Earth are aligned on the same axis Approximate). In 2015, moreover, the moon reached its perigee , that is to say its the smallest distance of Earth’s orbit on March 19 at 19:38 UT (8:38 p.m. to Paris time). His attraction to the waters of the oceans has been strengthened.
Since the first astronomical observations there for thousands of years, this period was marked by rites or celebrations. Especially in the northern hemisphere, late March is usually marked by the appearance of the first buds and “renaissance” of nature . The spring equinox is how the first day of the Iranian calendar traditional or sacred day in Zoroastrianism, the ancient religion of the Persians. Moreover, until the Renaissance, the New Year was often celebrated on March 1 in Europe. Pre-Columbian civilizations had also noticed this phenomenon. On the site Chichen Itza , Mexico, the Mayans built the pyramid El Castillo from the ninth to the twelfth century. At each equinox, the slanting rays of the sun striking the sun creates shadows voluntarily created by the architects: they remind a snake climbing up the building. In Europe, the Nordic civilizations celebrated Disablot at the time of the spring equinox. This party used to meet the female spirits and promote better harvest.
Did you know the existence of the meteorological spring? We entered this period, not to be confused with our spring schedule on Tuesday, March 1, 2016. And it will last until 31 May. But why this shift with the spring as everyone knows, that of the end of March? This is the need for meteorologists, can achieve average across fixed monthly periods This year, a funny trend reversal characterizes this weather season pass.: after a winter milder than average, we are in a cooler spring than others.
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