Solarkalender

SolarKalender is a term used for calendar systems that base their year on the solar year rather than the lunar cycle. The aim is to keep calendar dates in step with the Earth's revolution around the Sun, so that the progression of the seasons remains roughly constant from year to year.

In SolarKalender designs, the year length is 365 days in common years and 366 in leap years. To maintain this alignment, several approaches exist for distributing days into months and intercalary days. Some proposals use a regular set of intercalary days outside the 12 months, while others distribute extra days within months. Different rules for leap years have been proposed, ranging from simple four-year cycles to more complex corrections to match the solar year more closely over centuries.

SolarKalender has mainly appeared in theoretical discussions, reform proposals, or cultural experiments rather than widespread adoption. Advocates argue that it offers clearer correspondence with solstices, equinoxes, and seasons, while critics point to disruption of global timekeeping systems, software compatibility, and historical inertia.

There is no single standard SolarKalender; variations exist depending on whether the goal is exact astronomical alignment, ease of use, or compatibility with existing calendars. Related topics include the Gregorian calendar, leap year rules, and calendar reform efforts.