The most well-known source of light is the Sun, or Surya Dev in Hinduism. Suryadev has been worshiped in India since time immemorial following the traditional way of respecting and worshipping important forms of nature. Suryadev is a part of many festivals, including Pongal or Makar Sankranti, Chattha Puja, etc. The Surya Namaskara is a complete exercise procedure that is part of the daily-morning routine of many Indian homes. Will surely put up a post on this beautiful Yogic exercise soon... It is a well-known fact that light travels at a phenomenal speed of 3 x 10^8 metres/sec. This value is etched into the memory of students in their early years in school, and is useful is solving umpteen number of problems where the constant 'c' is used to denote the Speed of light. This value of the Speed of Light was established by the experiment conducted by Michelson and Morley, celebrated American Physicists in the 19th Century. But did you know that a very close value to the calculated one was determined in the 14th Century AD in India? The below sloka is part of the Rig Veda: Saint Sayanacharya (c.1300's), after reading the Rig Veda, gave the following comment: The above translates into: "It is to be noted that the Light due to the Sun travels 2202 Yojanas in half a Nimesha" Now for the calculation. Converting the units used in ancient India to those used presently : 1 Yojana = 9 miles 2202 Yojanas = 19818 miles 1 nimesha = 0.21333 seconds 1/2 nimesha = 0.10665 seconds Speed = distance / time = 19818 / 0.10665 = 185822 miles per second = 299044 kms per second. The value calculated by Michelson and Morley was approximated to 186000 miles per second, which is used these days along with the more common 3 x 10^8 metres per second. It must also be noted that Sayanacharya was only commenting on the Rig Vedic text. It is possible that even earlier interpretations and findings existed, but have not stood the tests of time. Thus, our Ancient Vedic Indians had established the Speed of Light much before scientists in other parts of the world ! This again proves the Scientific knowledge of Ancient India. Very Enlightening, isn't it?