Silbury Hill Sunset Azimuth on 1. September 3500BC vs 2024AD has difference of 16 degrees

[electroreceptive1970]

Silbury Hill Sunset Azimuth on 1. September 3500BC is 299.8.
Silbury Hill Sunset Azimuth on 1. September 2024AD is 283.3.
I cannot believe in such big difference.

From which year Stellarium works properly?
1500 AD?
1800 AD?

[gzotti]

There was no day called September 1, 3500BC for people living in 3500BC, so the problem was not relevant for them.

As we all know (do we?), before the Gregorian reform the Calendar was a mess. This is why we use the Gregorian calendar today. Read Appendix F in the User Guide for more information.