The Simplified Tropical Astronomical Year (STAY) Calendar was developed by Shriramana Sharma early in the first decade of the 21st century.
The twelve protomonths of 30 days each total 360 days in a solar year. Instead of placing the remaining 5 days in an arbitrary pattern like other calendars, the STAY calendar adds them to the part of the year when Earth is moving the slowest with regards to the Sun.
Aphelion[]
Imagine the orbit of Earth describing an ellipse around the Sun. The Sun sits in one of the two foci of that elliptical orbit.
When the Earth is circling the other focal point of the ellipse, it is situated further from the Sun. From the Sun point of view Earth is moving in Space slower (and more distant) at that time.
Earth is at its furthest when it crosses the line passing through the two foci. That is called the aphelion. It also crosses that line at the other end of the ellipse when it is the nearest to the Sun, that is the perihelion.
In the STAY calendar the month of the aphelion gets one more day, as well as the two months before and the two months that follow.
Definitions[]
For the STAY calendar, the day of the northward equinox is defined as the day measured in UT which contains the moment of the northward equinox.
The period from one northward equinox to the next is called the tropical year.
The day of aphelion is defined as the day measured in UT which contains the moment of aphelion. Note that STAY uses the uniformly progressing aphelion of the Earth-Moon barycenter and not the variable aphelion of the Earth itself.
New Year day is defined as 78 days before the day of the northward equinox.
After adding one day to five protomonths centered on the one containing the day of the aphelion, the protomonths become months. If the day of the aphelion falls outside any protomonth (day greater than 360) the last protomonth is used.
A leap day is added to the last month in case the 365th day is not the day immediately before the next New Year Day. That is the only month that can be 32 days long.
Notes of Interest[]
- UT is chosen because the same point in time or moment can fall on different days in different parts of the world. Hence it is necessary that the day is measured by a specific standard, in this case UT (Universal Time or clocktime at Greenwich).
- Although the long months (with 31 days) are intended to be "centered" on aphelion, if the aphelion occurs on the first or second day of a protomonth, it will enter the previous month, due to the extension of that month and its previous month by one day each. This does not matter.
- By definition the protomonths that take the extra 31st day are the one containing the aphelion and its two preceding and succeeding protomonths. It is not necessary for the two preceding and succeeding protomonths to be in the same year.
- The aphelion moves forward in the year to make one complete "round" in a period of about 21,000 years. The flexible definition of the STAY calendar make the 5 extra days track the aphelion wherever it goes! Defining the calendar based on the northward equinox and the aphelion makes sure that the calendar year length is true to the length of the astronomical year, and the structure is true to the velocity of revolution of the Earth.
Sample Year[]
| STAY Month | Length | Gregorian start date | Special days |
|---|---|---|---|
| January | 30 | 1 January | New Year day |
| February | 30 | 31 January | |
| March | 30 | 2 March | |
| April | 30 | 1 April | |
| May | 31 | 1 May | |
| June | 31 | 1 June | |
| July | 31 | 2 July | Aphelion |
| August | 31 | 2 August | |
| September | 31 | 2 September | |
| October | 30 | 3 October | |
| November | 30 | 2 November | |
| December | 30 | 2 December | New Year's Eve |
Weblinks[]
The same author also developed the leap-day Quasi-Lunar Calendar and otherwise promotes the Symmetry454 Calendar.