Brihat-Samhita is considered to be one of the most important contribution of Varahamihira. This epic consist of wide range of subjects comprising of human interest, including astrology, planetary movements, eclipses, rainfall, clouds, architecture, growth of crops, manufacture of perfume, matrimony, domestic relations, gems, pearls, and rituals. This work is an encyclopedia of astrological and other subjects of human interest. Whatever subjects the author takes up for delineation, whether it is eclipse, planetary movements, rainfall, cloud, architecture, water-divination or some other topic he discusses the same with thoroughness and mastery based on the knowledge of ancient shastras. Brihat Samhita is basically a monumental work on Mundane Astrology composed by Great Varahamihira. According to the scripture, the Sun is the Lord of the region at the source of the river Narmada; of Bengal, Kalinga; of Sakas; Yavanas; of Magadha, Sabra, Pragjyotisha, Cambodia and China.
Varahamihira , is one of the most popular compositions of astrology. Varahamihira’s efforts gave astrology a form of science. Just the appreciation will not be enough , for the contribution he made for astrology. While living in the famous astrology city of Ujjain , he introduced many Astrological Granthas. Even his father was a very popular astrologer of his times. He got his primary knowledge of astrology from his father only. Some of his writings are : Panchasiddhantika, Brahasthasahinta, Brijjataka, Laghujataka, Vivah Patala, Yoga Yatra, Samas Samhita, are some of the Scriptures composed by him.
He also worked with Aryabhatta , and composed many rules of astrology .Aryabhatta was his teacher, so he learned most of astrology rules from him only. Aryabhatta formerly worked on mathematics and numbers , and he learned mathematical calculations of astrology from Aryabhatta .
Varahamihira , with his rules and principles had already explained Newton’s Theory on “Gravity Rules “ He already knew that there is an earth’s attraction force that pulls objects towards it, and he named it as Gurutvakarshan.
Varahamihira introduced 4 type of months which includes Solar Month, Lunar Month , Yearly Month, and Fortnight Month. Varahamihira’s contribution other than astrology has also been into Astronomy, and Vriksha Ayurveda.