Sun directly over head
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So very practicle for this tricky tip of Jeff!
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Hi Jim, hi folks.
Equinoxes are normally on or around March 21st and September 21st.
Just ideas.
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@jean lemire said:
Hi Jim, hi folks.
Equinoxes are normally on or around March 21st and September 21st.
Just ideas.
typo by Jim?
his screenshot shows march 20 -
@unknownuser said:
@jean lemire said:
Hi Jim, hi folks.
Equinoxes are normally on or around March 21st and September 21st.
Just ideas.
typo by Jim?
his screenshot shows march 20depends on leap years - sometimes it's closer to the 20th.
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As said... typically the Equinox is on the 21st March/September.
However, it officially occurs when the Sun crosses the plane of the ecliptic in the constellation of Aries.
This might be on the 21st in the western Pacific while it's still the 20th in Europe/USA.
Or more rarely the 23rd in the western Pacific while it's still the 22nd in Europe/USA.
However these divergences are rare and usually it is on the 21st in Europe [even if it's just after or just before midnight GMT that day]...
Leap years every 4 years were introduced by Julius Caesar [Julian Calendar] to accommodate for the slide in the equinox/solstice dates that occurred when the earlier 365 days exactly were assumed in every year.
Unfortunately this over-compensated over hundreds of years and the equinox/solstice dates slowly slid in the other direction... Pope Gregory XIII readjusted the calendar by lopping out a block of days [10?] in 1582 [embarrassingly many puritan countries like UK/USA/Germany/Sweden/etc continued out of sync, but finally they too brought their calendars in line - many out of step with each other! - so by around 1752-3 all were synchronized [e.g. UK "lost" 11 days, but weirdly the "tax-year" that ran between vernal equinoxes slid to 5 April (where it remains to this day) because the UK's Treasury refused to 'lose' revenue in the 'change year' !!] - this also results in some dating anomalies during the overlapping years, depending on the calendar that is used].
Japan adopted it about a century later.
The Ottomans and Russia was much later still, coming into line in 1917+ with westernization and the birth of the USSR...
Greece was a laggard in 1923 !
So our modern view of the calendar is not so old...
This new 'Gregorian Calendar' set up rules to skip a leap now and again to avoid 'over-compensation'. Every year that is exactly divisible by 4 is a leap year, except for years that are exactly divisible by 100; the "centurial" years that are exactly divisible by 400 are still leap years. For example, the year 1900 was not a leap year; but the year 2000 was a leap year.
This in turn under-compensates and a further refinement, the designation of years evenly divisible by 4,000 as common (not leap) years, will keep the calendar accurate to within one day in 20,000 years.
But none of us will live that long !!! -
@jim4366 said:
So whatever, sketchup is insisting that equinox is Mar 20.
right.. but your original post says May 20
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