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Solar Calendar

Solar Calendar Research

Solar Calendar

A solar calendar is a timekeeping system based on a seasonal year of 365.24 days, the time it takes the earth to revolve once around the sun. The term “tropical solar calendar” refers to a calendar based on the earth’s orbit around the sun in relation to the equinox—the point where the orbit crosses the equator in the sky.

Origins of the Solar Calendar

It is believed the ancient Egyptians were the first to develop a solar calendar. Their fixed point of reference was the annual sunrise appearance of the Sirius, the Dog Star, in the east. This was a momentous event for them, as it heralded the annual flooding of the Nile.

The Egyptian calendar consisted of 365 days—12 months with 30 days each and 5 days added at the end of the year. However, since they didn’t take into account the extra ¼ of a day in a solar year, their calendar became inaccurate over time.

Development of Roman Calendar from The Egyptian Calendar

The Roman calendar was likely influenced by Julius Caesar’s time spent in Egypt. While pursuing his rival Pompeii to Egypt, he learned that the Egyptians were able to predict the annual flooding of the Nile River by the appearance of Sirius. This inspired him to scrap the lunar calendar of the Romans in favor of one based on Egypt’s solar calendar.

There are three variations of solar calendars: Tropical solar calendars, sidereal solar calendars and lunisolar calendars.

Tropical Solar Calendars

Generally, when someone refers to a solar calendar the reference is to the tropical solar calendar. This calendar tracks the position of the Earth as it revolves around the Sun. The term “tropical” refers to the length of time between two vernal equinoxes—365 days, 5 hours, 48 minutes and 46 seconds (365.2424 days) to be precise. Because the measurement is between the start of one summer season and another, the term “tropical” was apparently chosen to reference the warmth of the vernal season.

Tropical solar calendars have a year comprised of 365.24 days and will occasionally add an extra day to form a leap year in order to reconcile the number of days in the year with the solar year of 365.24 days. This process of adding a day is called “intercalation.”

Tropical solar calendars include:

Sidereal Solar Calendars

The term “sidereal” coms from the Latin sidus meaning “star.” So, it follows that a sidereal solar calendar is one based on the position of the earth in relation to fixed stars. Without getting into too much of the complexities, a sidereal year is 20 min and 24.5 seconds longer than the mean tropical year of 365.242189 days and is also 19 minutes and 57.8 seconds longer than the average Gregorian calendar year (365.2425).

Lunisolar Calendars

Lunisolar calendars are considered solar calendars, although the typical lunisolar calendar cannot specify the position of the earth on its revolution around the sun as well as a pure solar calendar can because its year is based on the lunar cycle.

The Solar Calendar vs The Biblical Calendar

Similarities between the solar calendar and the Biblical calendar begin and end with both accounting, to varying degrees, for solar cycles in their calculations for the length of a year. The calculations which both calendars are based on are complex and deeply rooted in each culture’s religious and agricultural traditions, as well as their observations of solar cycles.

Don Roth, an engineer by profession, has conducted extensive research into the Biblical calendar and its relationship to the Hebrew Calculated calendar. In his free 3-DVD collection, Don explains his mathematical proof for why the Hebrew Calculated calendar is true to the Biblical calendar and can be considered the true calendar of God.

Order your free DVDs revealing Don’s proof today, or to ask a question regarding the Biblical calendar and the solar calendar.

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