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Thread: Autumn equinox

  1. #1 Autumn equinox 
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    In the Gregorian calendar the date of the equinox of autumn happens on 21, 22, 23 or 24 September, in general on 22 or 23. It will return to fall on 21 only in 2092, and it will be the first time that this happens from the introduction of this calendar. It is verified on 24 instead in 1803, 1807, 1903, 1907, 1911, 1915, 1919, 1923, 1927 and 1931 and in the future in 2303!

    www.pierpaoloricci.it/dati/autunno_eng.htm


    My astronomical site:

    WWW.PIERPAOLORICCI.IT

    Also in English version

    www.pierpaoloricci.it/index_eng.htm
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  3. #2  
    Forum Freshman escAPEe's Avatar
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    The autumnal and vernal equinoxes, one in late September and the other in late March, are the two instances when our neighborhood star, the Sun, is at its zenith above the equator. Due to the inclination of the Earth, the Sun is directly above one hemisphere or the other the rest of the year.

    Theoretically (as close as the real world gets), we have 12 hours of day and 12 hours of night on that day. Although this "balance of light" seems special, it doesn't necessarily mean that gravity or the forces of the solar system are balanced. The notion that an egg can only be stood upright on its end during one of the equinox events is a myth.


    Standing on egg upright is possible not only on the vernal and autumnal equinox

    The total number of daylight hours in a 365-day year is always 4,380 and it doesn't matter where on the planet you call home. Arctic polar bears at the top of the northern hemisphere experience the same number of hours of daylight annually as do African elephants near the Equator and Antarctic penguins at the bottom of the southern hemisphere. Discounting local cloud cover, the sun shines for an equal amount of time on every square inch of the Earth's surface.

    Differences in daylight distribution around the globe are due to the Earth’s tilt on its axis. Because the Earth's axis of rotation is tilted 23.45 degrees from the plane described by its revolution around the sun, the daily hours of light on a planet-wide basis are distributed unequally through the year. At each of the poles, daylight comes in six-month blocks; at the Equator it varies by only a few minutes plus or minus 12 hours each day.


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  4. #3  
    Forum Ph.D. Leszek Luchowski's Avatar
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    Quote Originally Posted by escAPEe
    Discounting local cloud cover, the sun shines for an equal amount of time on every square inch of the Earth's surface.
    Correction: discounting local cloud cover and uneven terrain.
    Leszek. Pronounced [LEH-sheck]. The wondering Slav.
    History teaches us that we don't learn from history.
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