"Exact Science in the Srimad-Bhagavatam"
(1997). "Exact Science in the Srimad-Bhagavatam," Back to Godhead Magazine
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"A unit of measure known as the yogana hints at advanced astronomical knowledge in the ancient Vedic civilization."
"Turning to India, we find a unit of distance—called the yojana—that at first glance seems as ill defined as the medieval English furlong or foot. The yojana is defined to be either 16,000 or 32,000 hastas, where a hasta, or cubit, is 24 anulas, or fingers. That there were at least two sizes for the yojana is upheld by the writings of classical Indian astronomers. The fifth-century astronomer Aryabhata used a yojana of about 8 miles, and the astronomy text Surya-siddhanta a yogana of roughly 5 miles. . . [T]here is reason to think that these two yojanas use different standards for the hasta. Hiuen Thsang, a Buddhist pilgrim who visited India in the seventh century, wrote of yojanas in terms of a Chinese unit of measure called the li. He reported that a yojana consisted of 40 li according to Indian tradition but the measure in customary use equaled 30 li and the measure given in sacred texts was only 16. . . [By] using values for the Thang dynasty, when Hiuen Thsang lived, we can compute that the yojana of 16 li matches the small yojana of 4.6 miles. Could the yojana of 30 li match the larger yojana of 32,000 hastas? If it does . . . the larger yojana of 32,000 hastas then comes to 8.59 miles. At the equator, that is 1/8 of a degree of latitude. . . In summary, simple arguments from the testimony of Megasthenes and Hiuen Thsang enable us to reconstruct two closely related yojana values. Both are precisely defined as fractions of a degree of latitude at the equator. Both relate to the earth by multiples of 108 (namely 432 and 1728), and this relationship gives us a very accurate estimate of the polar flattening of the earth. Also, the length of the larger yojana is confirmed independently by an investigation comparing modern astronomy with the cosmology of the Bhagavatam."
Exact Science in the Srimad-Bhagavatam