Treatise on the Sun

Beneficial are the moments original: "muhūḥ" — a unit of time equal to 48 minutes; there are 30 in a day, but here sixty are mentioned, likely referring to the "ghati" or half-muhurta system. sixty in number, beginning with Suvijaya and others. This has been explained at length elsewhere; here it is stated briefly for practical use. 55 For the purpose of calculating the mean positions original: "madhyamānayana" — the mathematical process of finding the average position of a celestial body. of the planets original: "graha" — in Indian astronomy, this includes the Sun, Moon, the five visible planets, and the lunar nodes., at the end of the Golden Age original: "Krita Yuga" — the first and most perfect of the four cosmic ages., all the planets were in their mean positions. 56 Except for the nodes and the apogees original: "manda-ucca" — the point in an orbit furthest from the Earth., they were all at the beginning of the zodiac [zero degrees Aries]. The Moon's apogee original: "śaśāṅkocca" was at the beginning of Capricorn, and its node was at the beginning of Libra. 57 The others, being at zero degrees original: "niraṃśā", have reached their positions; those not mentioned here are the slow-moving ones. The Earth's diameter original: "bhūkarṇa" is eight hundred 3200 original: "śatātyaṣṭau" — literally 800. The gloss "3200" likely refers to a different unit or a specific commentary's calculation of the circumference. yojanas, but it is doubled [to 1,600] to find the diameter. 58 From the square of that [diameter], multiplied by ten, the square root of that result is the Earth's circumference original: "bhūparidhi" — this uses the ancient approximation of pi as the square root of 10.. That, multiplied by the sine of the latitude's complement and divided by the radius, gives the true local circumference original: "sphuṭa-bhū-paridhi" — the circumference of the Earth at the observer's specific latitude. at one's own place. 59 == Look at the year 1695/37?

By that [circumference], the distance from the meridian original: "deśāntara" — terrestrial longitude measured as a distance. is multiplied and then divided by the daily motion of the planet original: "grahabhukti". The result in minutes of arc original: "kalā" and so on, should be subtracted original: "praviśodhayet" from the mean planets if one is east of the prime meridian. 60 If one is situated to the west of the meridian line original: "rekhā-pratīcī", the correction should be added original: "prakṣipet" by those in their own country original: "svadeśajāḥ". The mountain of the gods [Meru] and the home of the demons [Lanka] are the two stations between which the meridian line lies. 61 [The line also passes through] Rohitaka Modern Rohtak., Avanti The city of Ujjain, the Greenwich of ancient Indian astronomy., and the nearby lake [Kurukshetra]. Beyond this, by observing the beginning and end of a lunar eclipse, the calculation is perfected. 62 If the eclipse happens earlier [than calculated for the meridian], one's own place is to the east of the center; if it hasn't happened yet, it is to the west. This is determined by the moment of the eclipse's contact or its clearance. 63

By the time units original: "nāḍī" — a unit of 24 minutes; 60 nadis make a day. representing the difference between these two, one should multiply the true circumference original: "paridhiṃ sphuṭaṃ". Dividing that by sixty, the result is the distance in yojanas A traditional unit of distance, roughly 8-13 kilometers. to the east or the west. 64 Using this distance, the correction for longitude should be applied for the benefit of calculations in one's own country. The start of the weekday occurs earlier in a country to the east, and later in a country to the west. 65 By the time units of that longitude, one should designate the time for the west. The motion for a desired time original: "iṣṭanāḍīguṇāmuktiḥ" is found by multiplying the daily motion by the desired time units and dividing by sixty to get the result in minutes and seconds.