Nilakantha Somayaji

Biographical details

Like several scholars of Kerala school of astronomy and mathematics, Nilakantha Somayaji documented precise chronological, familial and regional autobiographical details and commentaries of his work using the Katapayādi systems.

In one of his works titled Siddhanta-star and also in his own commentary on Siddhanta-darpana, Nilakantha Somayaji stated that he was born on Kali-day 1,660,181 which works out to 14 June 1444 CE. A contemporary reference to Nilakantha Somayaji in a Malayalam work on astrology implies that Somayaji lived to a ripe old age even to become a centenarian. Sankara Variar, a pupil of Nilakantha Somayaji, in his commentary on Tantrasamgraha titled Tantrasamgraha-vyakhya, points out that the first and last verses of Tantrasamgraha contain chronograms specifying the Kali-days of the commencement (1,680,548) and of completion (1,680,553) of Somayaji's magnum opus Tantrasamgraha. Both these days occur in 1500 CE.

In Aryabhatiya-bhashya, Nilakantha Somayaji has stated that he was the son of Jatavedas and he had a brother named Sankara. Somayaji has further stated that he was a Bhatta belonging to the Gargya gotra and was a follower of Asvalayana-sutra of Rigveda. References in his own Laghuramayana indicate that Nilakantha Somayaji was a member of the Kelallur family (Sanskritised as Kerala-sad-grama) residing at Kundagrama, now known as Trikkandiyur in modern Tirur, Kerala. His wife was named Arya and he had two sons Rama and Dakshinamurti.

Nilakantha Somayaji studied vedanta and some aspects of astronomy under one Ravi. However, it was Damodara, son of Kerala-drgganita author Paramesvara, who initiated him into the science of astronomy and instructed him in the basic principles of mathematical computations. The great Malayalam poet Thunchaththu Ramanujan Ezhuthachan is said to have been a student of Nilakantha Somayaji.

The epithet Somayaji is a title conferred upon a Nambudiri Brahmin who has performed the vedic Somayajña (or Somayāga) ritual, indicating that Nilakantha completed this ritual. In Malayalam, the Sanskrit term Somayāji evolved phonologically as Comātiri (or Chomāthiri).

Somayāji’s "Āryabhaṭīyabhāṣya" is the most extensive commentary on Āryabhaṭīya. He takes all pains to expose the rationale and the objective behind the statements and observations made by Āryabhaṭa.

Nilakantha Somayaji as a polymath

Nilakantha's writings substantiate his knowledge of several branches of Indian philosophy and culture. It is said that he could refer to a Mimamsa authority to establish his view-point in a debate and with equal felicity apply a grammatical dictum to the same purpose. In his writings he refers to a Mimamsa authority, quotes extensively from Pingala's chandas-sutra, scriptures, Dharmasastras, Bhagavata and Vishnupurana also. He cites many passages from classical works on Mīmāṃsā system of philosophy for stressing the need for continuity of investigation. He cites passages from Śabarasvāmibhāṣya, Bṛhaṭṭīkā, Tantravārttika, Paritoṣamiśra’s Ajitā commentary, the Vijayā commentary on Ajitā and Pārthasārathimiśra’s Nyāyaratnamālā. Sundararaja, a contemporary Tamil astronomer, refers to Nilakantha as sad-darshani-parangata, one who had mastered the six systems of Indian philosophy.

Astronomy

In his Tantrasangraha, Nilakantha revised Aryabhata's model for the planets Mercury and Venus. According to George G. Joseph his equation of the centre for these planets remained the most accurate until the time of Johannes Kepler in the 17th century.

In his Aryabhatiyabhasya, a commentary on Aryabhata's Aryabhatiya, Nilakantha developed a computational system for a partially heliocentric planetary model in which Mercury, Venus, Mars, Jupiter and Saturn orbit the Sun, which in turn orbits the Earth, similar to the Tychonic system later proposed by Tycho Brahe in the late 16th century. Most astronomers of the Kerala school who followed him accepted this planetary model.

Somayaji consistently argued that astronomical parameters and computational models must undergo periodic revision based on continuous observations (dṛk-gaṇita-aikya). He also asserts that, when observation (pratyakṣa) and rationale (yukti) contradict the practiced tradition, the observable reality must guide the mathematical model. His specialized work Jyotirmīmāṃsā explicitly establishes a scientific epistemology for astronomy (jyotiḥśāstra). He utilized the methods of the Mīmāṃsā school of Indian philosophy to justfy continuous obervational verification (parīkṣā) instead of dogmatic traditional adherence.