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== कालमानम् ॥ Kalamanam ==

== कालमानम् ॥ Kalamanam ==

Kalapramana or the duration of time and measurements, are variously described in different texts. The calculations are based on nakshatras, suryodaya, chandra (moon), planetary transits for earthly time measurements. Thus we have nakshatramana, sauramana, chandramana etc ways to measure time. Astronomy and Astrology texts such as Surya Siddhanta, deal extensively with the topic of time and its calculations ranging from less than a second to trillions of years. Kala is classified into two according to Surya Siddhanta as follows  <blockquote>लोकानामन्तकृत्कालः कालोन्यः कलनात्मकः । स द्विधा स्थूलसूक्ष्मत्वान्मू्र्त्तश्चामूर्त उच्यते॥ (Sury. Sidd. 1.10) (Page 5 of Book in Reference<ref name=":4">Mahaviraprasad, Shrivastav. (1982 2nd Edition) ''Surya Siddhanta with Vijnana Bhashya, Khanda One.'' Allahabad: Dr. Ratnakumari Svadhyaya Sansthan</ref></blockquote>Summary : Kala is (1) Anadi and Ananta (is continuous and endless) which destroys all animate and inanimate things (2) Kalanatmaka (that which can be known). The later kind of time which is measurable time is again of two kinds. (1) Sthula (2) Sukshma. Sthula time is that which can be measured hence called Murta, while Sukshma is (a small time scale) which cannot be measured (immeasurable due to its smallness) hence called Amurta.<ref name=":4" /><ref name=":5">Pt. Bapu Deva Sastri (1861) ''Translation of the Surya Siddhanta from the Sanskrit.'' Calcutta : Asiatic Society of Bengal</ref>

Kalapramana or the duration of time and measurements, are variously described in different texts. The calculations are based on nakshatras, suryodaya, chandra (moon), planetary transits for earthly time measurements. Thus we have nakshatramana, sauramana, chandramana etc ways to measure time. Astronomy and Astrology texts such as Surya Siddhanta, deal extensively with the topic of time and its calculations ranging from less than a second to trillions of years. Kala is classified into two according to Surya Siddhanta as follows  <blockquote>लोकानामन्तकृत्कालः कालोन्यः कलनात्मकः । स द्विधा स्थूलसूक्ष्मत्वान्मू्र्त्तश्चामूर्त उच्यते॥ (Sury. Sidd. 1.10) (Page 5 of Book in Reference<ref name=":4">Mahaviraprasad, Shrivastav. (1982 2nd Edition) ''Surya Siddhanta with Vijnana Bhashya, Khanda One.'' Allahabad: Dr. Ratnakumari Svadhyaya Sansthan</ref>)</blockquote>Summary : Kala is (1) Anadi and Ananta (is continuous and endless) which destroys all animate and inanimate things (2) Kalanatmaka (that which can be known). The later kind of time which is measurable time is again of two kinds. (1) Sthula (2) Sukshma. Sthula time is that which can be measured hence called Murta, while Sukshma is (a small time scale) which cannot be measured (immeasurable due to its smallness) hence called Amurta.<ref name=":4" /><ref name=":5">Pt. Bapu Deva Sastri (1861) ''Translation of the Surya Siddhanta from the Sanskrit.'' Calcutta : Asiatic Society of Bengal</ref>

First kind of Kala cannot be imagined as one cannot know its origin and end, it is indivisible and exists as is even though Brahmas and Indras pass, creation and destruction take place, hence Mrtyu is called also called Kala.<ref name=":4" />

First kind of Kala cannot be imagined as one cannot know its origin and end, it is indivisible and exists as is even though Brahmas and Indras pass, creation and destruction take place, hence Mrtyu is called also called Kala.<ref name=":4" />

Various texts such as Manusmrti, Bhagavata Purana, Vishnu purana, Bhavishya purana and Mahabharata, also deal elaborately with the creation of the universe, of the division of the movement of the Universe into specified periods called the Yugas.  

Various texts such as Manusmrti, Bhagavata Purana, Vishnu purana, Bhavishya purana and Mahabharata, also deal elaborately with the creation of the universe, of the division of the movement of the Universe into specified periods called the Yugas. Indian time scales are unique in that they account for the cyclic and linear aspects as seen from the astronomical texts.   

== Yuga System ==

== Yuga System ==

On the macroscopic scale of time, the yuga system is highly evolved in the Indian Astronomy. Many important elements of planets and other parameters are given in terms of the number of revolutions in the course of a long period of time called '''yuga'''. The concept of Yugas is extensively discussed in various puranas.     

On the macroscopic scale of time, the yuga system is highly evolved in the Indian Astronomy. Many important elements of planets and other parameters are given in terms of the number of revolutions in the course of a long period of time called '''yuga'''. The concept of Yugas is extensively discussed in various puranas.     

While in the [[Vedanga Jyotisha (वेदाङ्गज्योतिष्)|Vedanga Jyotisha]] the word yuga was used to mean a period of 5 years, in later works the word meant a large period of time. Yugas of large periods of time have been used to indicate the rates of motion of planets and other important points of astronomical significance. This technique enabled them to express these constants as integers, though very large, thus avoiding very inconvenient fractions.<ref name=":0">Balachandra Rao, S. (2017 Third Edition) Indian Mathematics and Astronomy. Benguluru : Bhavan's Gandhi Center of Science & Human Values</ref> Indian time scales are unique in that they account for the cyclic and linear aspects as seen from the astronomical texts.

While in the [[Vedanga Jyotisha (वेदाङ्गज्योतिष्)|Vedanga Jyotisha]] the word yuga was used to mean a period of 5 years, in later works the word meant a large period of time. Yugas of large periods of time have been used to indicate the rates of motion of planets and other important points of astronomical significance. This technique enabled them to express these constants as integers, though very large, thus avoiding very inconvenient fractions.<ref name=":0">Balachandra Rao, S. (2017 Third Edition) Indian Mathematics and Astronomy. Benguluru : Bhavan's Gandhi Center of Science & Human Values</ref>

=== Yuga in Vedas ===

=== Yuga in Vedas ===

Present Chaturyuga = Kaliyuga (4th of the Chaturyugas)   

Present Chaturyuga = Kaliyuga (4th of the Chaturyugas)   

The later time points in Kali yuga are calculated in our calendars and Panchangas.  

The later time points in Kali yuga are calculated in our calendars and Panchangas. Accurate prediction of the ending moment of tithis, sankramana (transit of sun across rasis), eclipses etc seem to have contributed in a big way to the growth of mathematics in India.   

 

 

== शकाः ॥ Sakas or Eras ==

== शकाः ॥ Sakas or Eras ==

!Bhagavata Purana<ref name=":3" />

!Bhagavata Purana<ref name=":3" />

!Vaiseshika Darshana<ref name=":6" />

!Vaiseshika Darshana<ref name=":6" />

!Vedanga Jyotisha<ref>Kuppanna Sastry, T. S. and Sarma, K. V. (1985) ''Vedanga Jyotisa of Lagadha in its Rk and Yajus Recensions with the translation and notes of Prof. T. S. Kuppanna Sastry.'' New Delhi : Indian National Science Academy</ref>

!Vedanga Jyotisha<ref name=":8">Kuppanna Sastry, T. S. and Sarma, K. V. (1985) ''Vedanga Jyotisa of Lagadha in its Rk and Yajus Recensions with the translation and notes of Prof. T. S. Kuppanna Sastry.'' New Delhi : Indian National Science Academy</ref>

!Surya Siddhanta<ref name=":5" />

!Surya Siddhanta<ref name=":5" />

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