<p>I am trying to find information on the equinox/solstice dates before 1600, more exactly referring up to 10,000 BCE so as to create a sort of calculator on an Excel spreadsheet.</p>

<p>I have read about the SOLEX, but it is not available anymore. Is there any other software that can accurately (as possible, of course) predict the equinoxes and solstices keeping in mind the perihelion/aphelion effects on the period between equinoxes/solstices?</p>

<p>If you believe it is possible to try a formula on excel to calculate these dates for me (instead of just copying down the dates into a database), please keep in mind that my mathematical/programming knowledge is limited. </p>

CC BY-SA 3.0
2016-01-28T12:06:51.520Z
@barrycarter: that's how I started, really. But after inserting a couple of thousand years in, I realised that a formula might be faster and less prone to mistakes (it's tiring and numbers start to look alike).
SC for reinstatement of Monica
CC BY-SA 3.0
2016-01-01T09:21:51.570Z
If you go back 10,000 years, you're going to have to manually add 3 leap years (or subtract 3 leap years, I'm not sure which).    But with the Gregorian calendar you'd still be off by a bit over 3 days over 10,000 years.   The problem is that 365 days (or 365.2425 days) doesn't fit exactly.   The specific dates would depend on which years you inserted the 3 leap years.    

http://www.timeanddate.com/date/perfect-calendar.html
userLTK
CC BY-SA 3.0
2017-10-29T19:07:09.680Z
culturediff.org has the dates accurately from 2025 to -4700.
Laurence Crossen
<orbit><the-sun><earth>
Are there accurate equinox and solstice predictions for the distant past?
SC for reinstatement of Monica
# Are there accurate equinox and solstice predictions for the distant past?

(Asked by: username_0 on 2015-12-28)

I am trying to find information on the equinox/solstice dates before 1600, more exactly referring up to 10,000 BCE so as to create a sort of calculator on an Excel spreadsheet.

I have read about the SOLEX, but it is not available anymore. Is there any other software that can accurately (as possible, of course) predict the equinoxes and solstices keeping in mind the perihelion/aphelion effects on the period between equinoxes/solstices?

If you believe it is possible to try a formula on excel to calculate these dates for me (instead of just copying down the dates into a database), please keep in mind that my mathematical/programming knowledge is limited.

**Tags:** orbit, the-sun, earth
> **Comments:**
> **username_1**: If you go back 10,000 years, you're going to have to manually add 3 leap years (or subtract 3 leap years, I'm not sure which).    But with the Gregorian calendar you'd still be off by a bit over 3 days over 10,000 years.   The problem is that 365 days (or 365.2425 days) doesn't fit exactly.   The specific dates would depend on which years you inserted the 3 leap years.      http://www.timeanddate.com/date/perfect-calendar.html  
> **username_0**: @barrycarter: that's how I started, really. But after inserting a couple of thousand years in, I realised that a formula might be faster and less prone to mistakes (it's tiring and numbers start to look alike).  
> **username_2**: culturediff.org has the dates accurately from 2025 to -4700.  

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## 0 answers

