Discernment of the Truth of Astronomical Principles

The rotations involving the Sun and the earth's movement original: Sāvyākabhubhramāḥ; referring to the combined motion of the earth's rotation relative to the Sun are considered. If the Mean Sun original: madhyārka; the theoretical sun moving at a constant speed has reached the desired point at the intended time, then, due to the difference in time, the Civil Day-count Sāvana Ahargaṇa|The total number of civil days elapsed since a fixed epoch, usually the start of the Kali Yuga is established from the union of three factors. In that civil day-count, the rotations are not merely the cycles of the Mean Sun, but the sum of three elements: the total rotations of the star-sphere, the Sun’s own revolutions, and the minutes of the Mean Sun converted into time-units original: asavaḥ; breath-units or sidereal seconds.

The Civil Day-count derived from these three is considered the Actual original: vāstava count. It is established through distinct methods. Through the Rule of Three Trairāshika|A mathematical proportion: if A gives B, what does C give?, the position of the Mean Sun at the time of sunrise is determined as the Actual position. In some systems, this is calculated using the "Mean Civil Day," but the result must correspond to the actual time of sunrise. Some may argue that to achieve this "actual" state, a specific correction for the Equation of Time Udayāntara|The difference between mean solar time and true solar time caused by the earth's orbital eccentricity and the tilt of its axis is necessary.

To this, it is said: My preferred method for reaching the "actual" result does not rely on whether a specific day is counted as "real" or "not real" in a purely theoretical sense. For instance, in the previously mentioned system, the day-count is defined by one rotation, one revolution, and the intersection of the Mean Sun’s minutes. In the Non-Actual original: avāstava; here referring to the mean or simplified calculation method, one simply considers the day-count as one revolution and the basic minutes of the Mean Sun. The difference between the Actual Civil Day and the Non-Actual one is a period of twenty-seven units?, during which time units like Lunar Days original: tithi and smaller fractions of time may be lost or diminished.

Furthermore, there may be a greater or lesser internal difference. According to those who follow the "Network of Time" original: tanjāla; likely referring to a specific school of astronomical calculation, this difference must be clearly defined. In the Sidereal Year original: nirayana-varṣa; a year measured relative to fixed stars, without accounting for the precession of the equinoxes, if one only adds the extra cycles of the celestial circle to the mean measure, the Civil Day-count will not be accurate.

Those who speak clearly on the matter state that the civil day is determined by the Sun’s position including precession original: sāyana; tropical longitude and its corresponding time-units. If one calculates the Equation of Time original: udayāntara based on the Sun, even that might be considered "not real" if it does not lead to the Actual Day-count. This would contradict the sacred traditions. In reality, in the solar and lunar systems, the cause of the day and night is the Sun’s own motion. Just as the civil days are determined by the movement of the lunar day through twelve degrees of separation, they are established as "actual" at the desired time through mutual proportion. This is not the case in the purely sidereal system. Therefore, the day-and-night cycle depends on its own motion, and the proportions derived from it at a given time are not "actual" unless they align with the reality of the celestial sphere. This is established through the Intercalary Months original: adhimāsa; extra months added to the lunar calendar to align it with the solar year and the Omitted Days original: avama; days skipped in the lunar calendar to maintain alignment. Through the relationship of the remaining fractions of these omitted days, the Civil Days are calculated as they appear at the horizon at the time of the Mean Sun’s rise. This is what makes them Actual.