"This is the one exception every 400 years."
I still count 3 exceptions to the Julian calendar every 400 years. Count them.
You haven't explained the "reference calendar" and why I would be wishing to change it. What did that mean?
How else can this be construed that isn't an erroneous statement? The "1" is literally taken to mean "one extra day" and this would even be worse than the Julian calendar. Even if you said "1 less", that would still be wrong. Neither case matches what the Gregorian reforms prescribe.
I am also...
The "mean tropical year" is based on the mean sun, and is not exactly equal to any of the times taken to go from an equinox to the next or from a solstice to the next.
Between two Southern solstices ( year 2000 ) equals 365.242740 days
So I guess two times around winter, the Gregorian would...
There is also the magical latitude 35.26 ° , quite near my home. From there, you can set down a cube and have the axis point to the north star. Same goes for the octahedron! These solids could go farther and have sundials affixed to each face. These things set flat at this latitude.
Calendars that reckon the year by counting lunar months are called luni-solar. Calendars that reckon a fixed number of months are lunar calendars. It is more usual to say that a common year ( luni-solar ) has 12 months with leap months added than a 13 month year that is truncated, because the...
A lunar calendar of 13 months would track 13 months regardless of the Spring Equinox. I didn't find "13 months" mentioned on the reference. What are you talking about?
SSM is the standard solar model not the standard stellar model. How could there be a standard stellar model if there are so many different kinds of stars?
The Lane-Emden equation is an equation that merges Newtonian gravity with the ideal gas law. It is instructive to study its derivation...