The study of Jyotish is dependent on study of movement of heavenly bodies and division of time.
The division of time appears in all the ancient Hindu scriptures to its minutest factor, the science is certainly of an antiquity beyond human comprehension. Indian astronomers developed spherical geometry (called gola ganita) while others were struggling with arithmetic.
Let us see the division of time that was visualized by the ancient sages and which finds mentions in many of the Puranas and other ancient texts, to get an idea of the depth of their understanding of the ever elusive dimension, time.