Science and technology in Ancient India covered many major branches of human knowledge and activities including mathematics, astronomy, physics, metallurgy, shipbuilding and navigation etc.
Ancient India's contributions to astronomy are well known and documented. The earliest references to astronomy are found in Rig-Veda dated between 4500 BC.The science of astronomy continued to develop independently and culminated in original findings such as the calculation of occurrence of eclipses, calculation of earth's circumference, theorizing about gravity, determining the number of planets in the solar system. There are astronomical references of chronological significance in the Vedas. The Aitareya Brahmana states that the sun never sets nor rises. When people think the sun is setting it is not so they are mistaken. This indicates that sun is stationary (hence the earth is moving around it) which is elaborated in a later commentary Vishnu Purana that states the sun is stationed for all time in the middle of the day. Of the sun that is always in one and the same place there is neither setting nor rising.
Yajnavalkya recognized that the earth was round and believed that the sun was the center of the spheres as described in the Vedas at the time. His astronomical text Shatapatha Brahmana stated the sun strings these worlds the earth, the planets, the atmosphere to himself on a thread. He recognized that sun was much larger than the earth that would have influenced this early heliocentric concept. He accurately measured the relative distances of the sun and the moon from the earth as 108 times the diameter of these heavenly bodies almost close to the modern measurements of 107.6 for the sun and 110.6 for the moon.
The Indian astronomer mathematican Aryabhatta (476-550) in his Aryabhattiam propounded a mathematical model in which the earth was taken to be spinning on its axis and the periods of the planets were given with respect to the stationary sun. He was also the first to discover that the light from the moon and the planets were reflected from the sun and that the planets follow an elliptical orbit around the sun and thus came up with an elliptical model of the planets on which he accurately calculated many astronomical constants such as the times of the solar and lunar eclipses and instantaneous motion of the moon.
Brahmagupta (598-668) was the head of the astronomical observatory at Ujjain and during his tenure there wrote a text on astronomy the Brahmasphutasiddhanta in 628. Bhaskara the head of the astronomical observatory at Ujjain continued the mathematical tradition of Brahmagupta.He wrote the Siddhanta-Shiromani which consists of two parts Goladhyaya and Grahaganita.He also expanded on Aryabhata model in his treatise where he mentioned the law of gravity discovered that the planets do not orbit the sun at uniform velocity and accurately calculated many astronomical constants based on this model such as the solar and lunar eclipses and the velocities and instantaneous motions of the planets. The other important names of historical astronomers are Madhava and Nilakantha Somayaji.
In Ancient India the philosophical schools of Samkhya and Vaisheshika from 6-5th BC developed theories on light. According to Samkhya School light is one of the five fundamental subtle elements out of which emerge the gross elements. The atomicity of these elements is not mentioned and it appears that they were actually taken to be continuous. According to the Vaisheshika School motion is defined in terms of the movement of the physical atoms and it appears that it is taken to be non instantaneous. Light rays are taken to be a stream of high velocity of tejas(fire ) atoms. The particles of light can exhibit different characteristics depending on the speed and the arrangements or the tejas atoms. The Vishnu Purana refers to sunlight as the seven rays of the sun.
The science of medicine in ancient India is known as Ayurveda the science of life or longevity in Sanskrit from ayur (age or life) and veda (knowledge). Ayurveda constitutes ideas about ailments and diseases, their symptoms, diagnosis and cure and relies heavily on herbal medicine including extracts from several plants. Ancient scholars of India like Atreya and Agnivesha have dealt with principles of Ayurveda. Charaka consolidated their works and other developments into a compendium of ayurvedic principles and practices Charaka Samhita .It deals with variety of matters covering physiology, digestion, metabolism and immunity. Advances in the field of medical surgery were also made in Ancient India including plastic surgery, extraction of cataracts and even dental surgery. The medical theoretician and practitioner Shushruta lived around the 6th century BC in Kasi.He wrote the medical compendium Shushta Samhita describing at least seven branches of surgery. Shushruta also describes over 120 surgical instruments, 300 surgical procedures and classifies human surgery in 8 categories. He is also known by the by the title Father of Surgery. Both Sushruta and Charaka mention the use of medicinal liquors to produce insensibility to pain.
Metallurgy has remained central to all civilizations from the Bronze Age and the Iron Age and later it is believed that the basic idea of smelting reached ancient India from Mesopotamia and the near east. In the 5th century BC the Greek historian Herodotus observed that the Indian and Persian army used arrows tipped with iron. An important Indian metallurgist and alchemist was Nagarjuna (931) who wrote the treatise Rasaratnakara that deals with preparations of rasa (mercury) compounds. It gives a survey of the status of metallurgy and alchemy in the land. Extraction of metals such as silver, gold, tin and copper from their ores and their purification were also mentioned in the treatise. Ancient India's advanced chemical science also finds expression in activities like distillation of perfumes and fragrant ointments, manufacturing of dyes and chemicals, preparation of pigments and colors and polishing of mirrors.
Mechanical and production technology of ancient India ensured processing of natural produce and their conversion into merchandise of trade, commerce and export. A number of travellers and historians including Ptolemy, Marco Polo, AL Baruni, Megasthanese have indicated a variety of items that were produced, consumed and exported around by merchants in Ancient India.
The science of shipbuilding and navigation were well known to ancient India. Sanskrit and Pali texts are replete with maritime references. India traded with several nations across the Bay of Bengal like Cambodia, Java, Sumatra,Borneo and even China and across the Arabian Sea like Egypt,Persia and Mesopotamia. A panel found in Mohenjodaro depicts a sailing craft.