Aryabhata, who lived in the 5th century CE, is widely regarded as the father of Indian astronomy. He made significant contributions to various fields of astronomy, including trigonometry, algebra, and planetary motion.

Aryabhata proposed the heliocentric model of the solar system, which places the Sun at the center and the Earth and other planets revolving around it. This model was later developed and refined by other astronomers, including Copernicus and Galileo.

The gnomon, a simple instrument consisting of a vertical rod or pillar, was widely used by ancient Indian astronomers for observations. It was used to measure the altitude of celestial objects, determine the time of day, and study the movement of the Sun and stars.

The Surya Siddhanta, an ancient Indian astronomical text, provides detailed descriptions of various astronomical instruments, including the gnomon, astrolabe, and armillary sphere. It also contains information about astronomical calculations, planetary motion, and eclipses.

Jantar Mantar is an ancient Indian observatory located in Delhi, India. It was built by Maharaja Jai Singh II in the 18th century and consists of a collection of architectural astronomical instruments, including sundials, quadrants, and astrolabes. These instruments were used for various astronomical observations and calculations.

Lagadha, an ancient Indian astronomer, developed the concept of the zodiac and divided the ecliptic into 12 equal parts, known as the zodiac signs. This division was based on the positions of the Sun, Moon, and planets in the sky.

The Rig Veda, one of the oldest and most sacred texts of Hinduism, primarily consists of religious hymns and prayers. While it does contain some references to astronomical phenomena, its primary focus is on religious and spiritual matters.

Aryabhata developed a method for calculating the circumference of the Earth using the angle of depression of a star. He measured the angle between the horizon and a star known as Dhruva (Polaris) and used this measurement to estimate the Earth's circumference.

The Surya Siddhanta, an ancient Indian astronomical text, contains detailed instructions for constructing various astronomical instruments, including the gnomon, astrolabe, and armillary sphere. These instruments were used for observations and calculations related to astronomy and astrology.

Bhaskara II developed a theory of planetary motion that included elliptical orbits. He proposed that planets move in elliptical paths around the Sun, a concept that was later refined and formalized by Johannes Kepler.

The Atharva Veda, one of the four Vedas in Hinduism, primarily consists of magical spells, charms, and incantations. While it does contain some references to astronomical phenomena, its primary focus is on practical magic and rituals.

Brahmagupta developed a method for calculating the time of sunrise and sunset based on the latitude and longitude of a location. This method was later adopted by astronomers in other parts of the world and is still used today.

The Surya Siddhanta, an ancient Indian astronomical text, provides detailed descriptions of various astronomical phenomena, including eclipses, planetary conjunctions, and the motion of the Sun and Moon. It also contains information about astronomical calculations and the use of astronomical instruments.

Aryabhata developed a method for calculating the distance between the Earth and the Moon. He used the angle between the Moon and a star known as Rohini (Aldebaran) to estimate the Moon's distance from the Earth.

The Yajur Veda, one of the four Vedas in Hinduism, primarily consists of ritual instructions and formulas used in various religious ceremonies. While it does contain some references to astronomical phenomena, its primary focus is on ritual practices and procedures.