Astronomical-Mathematical Theorem on the Growing Difference Between the Solar and Lunar Years – English version (PDF)

Have you ever wondered why calendars require leap days, leap months, and complicated rules?

This document answers this question in a clear, mathematical, and logical way.

What will you find in this file?

• A precise theorem – one sentence that changes the way you think about calendars.
• A rigorous mathematical proof – based on astronomical data (IERS, epoch J2000.0).
• A final conclusion – why the solar-lunar calendar is inherently flawed and what this means for calendar construction.

Who is this document for?

• For astronomy and mathematics enthusiasts – who want to understand why calendars are imperfect.
• For those interested in the history and construction of calendars – from antiquity to the present.
• For calendar creators and researchers of time reckoning systems – seeking solid theoretical foundations.
• For teachers and students – as teaching material for astronomy, mathematics, or physics classes.
• For anyone looking for a logical, scientific explanation – why a strictly solar calendar is the only coherent solution.

What makes this document stand out?

• Conciseness – the entire proof fits on one page.
• Correctness – based on recognized astronomical data (IERS, epoch J2000.0).
• Accessibility – written so that it can be understood without advanced mathematical knowledge.

Technical details:

• Format: PDF
• Number of pages: 1
• Language: English
• Author: Henryk Skowroński (Solar Calendar)
• Contact: solar.calendar.dev@proton.me