Purnamadah purnamidam | Purnat purnamudachyate
Purnasya purnamadaya | Purnamevavashishyate.
[infinite Brahman - Isha Upanishad]
"That [Brahman, the Supreme Being] is infinite (full, complete). This [physical Universe] is infinite. From the infinite [Brahman], the infinite [Universe] came into being. The infinite [Brahman] having the infinite [Universe] taken away, remains infinite."
Universe is immense and we donot know whether the Universe has an "end" or not; we are not completely sure even of the full meaning of the question.
The Universe is probably 10-20 billion years old. The entire Universe is not static, but expanding. Universe contains objects such as Galaxies (some exploding and colliding); Neutron Stars and Pulsars; Quasars; and Black Holes
Our Solar System located at the edge of the Milkiway disk of stars is probably 4-5 billion years old.
The Milkiway, bright band of stars is estimated to be about 50000 light years in its diameter.
There are 200 billion "Suns" in a galaxy like our own Milky Way, a spiral galaxy.
Astronomers can see billions of galaxies.
Around 10000 stars visible to our naked eye are generally within a few hundred light years around us.
Some giant stars are located nearly 1000 light years are also visible to naked eye.
The Solar System is the "system" of planets, asteroids, and comets that orbit around our Sun.
Newer suns (such as our Sun) are in the spiral arms. Older suns are in the center of the galaxy.
Our Solar System is in the Orion Arm of the Milky Way.
- All heavenly bodies are assumed at different distance, based on the appearance. So the order of mandalam is surya, chandra, nakshadra, pudan, sukra... Varahamira/Baskara corrected this. But our texts have not been updated.
- Water is the key element in earth. Some texts are interpreted to mean that all heavenly bodies starting with soma/chandra came from water.
Vedic Astronomical Values
The Sanskrit word "jyotish" referred to the study of astronomy and astrology both; as in other cultures of the day, astronomy and astrology were considered inseperable. The astronomical methods outlined in the Vedanga-jyotisha were thus in use in India for a long time. It is clear in the text of Surya Siddhanta and the current practice of Indian astrology that sidereal measurements are of primary importance. Tropical measurements are also used but in a secondary way.
- Twelve spokes, one wheel, navels three. Who can comprehend this? On it are placed together three hundred and sixty like pegs. They shake not in the least. (Dirghatama Rishi, Rig Veda 1.164.48)
- One of the oldest works on jyotish is the Vedanga-jyotisha, probably written by Lagadha. He most likely compiled techniques and observations from manuscripts that existed in his day. The work that survives was probably rewritten by later astronomers around 400 BCE, judging from the work's clasical (post-Vedic) Sanskrit. However, this work contains an observation that the Winter Solstice occurred when the star Shravishtha (α Delphini) was on the horizon. This dates the original work around 1400 BCE, placing it in the late Vedic period.
- A seven named horse does draw this three naved wheel… Seven steeds draw the seven wheeled chariot… Wise poets have spun a seven strand tale around this heavenly calf, the Sun. (Dirghatama Rishi, Rig Veda 1.164.1 5). Seven visible planets.
- The number seven related to the Sun has much significance when understanding the third mean solar motion. During the course of 10,000 years there are seven rotations of the third mean solar motion. For a single year the count is 0.2563795 diurnal revolutions of the earth. For two years it is .512759 and so on. One complete rotation (to equal 366.2564…) of the third motion takes 1428.571429 [10000/7] sidereal years.
- Yuga in mythology is a large number. Sun (our whole solar system) orbits around the center of the Milky Way Galaxy at 828,000 km/hr. But even at that high rate, it still takes us about 230 million years to make one complete orbit around the Milky Way
- Axial precession is the movement of the rotational axis of an astronomical body, whereby the axis slowly traces out a cone. In the case of Earth, this type of precession is also known as the precession of the equinoxes or precession of the equator. Earth goes through one such complete precessional cycle in a period of approximately 26,000 years, during which the positions of stars as measured in the equatorial coordinate system will slowly change; the change is due to the change of the coordinates. IT takes 26,471 years to come to same position. Every 2206 years, starting rasi for solar year will move by one.
Mandala means Circle, Saptarishi means 7 sages. The 7 stars of what we call the Great Bear (Ursa Major) or Big Dipper in English, have been called or named after The Seven Sages or the Sapta Rishis in Indian Astronomy. (Interestingly Sapta Rsha (Seven Sages), can have been distorted to Sapta Rksha (Seven Bears) which could have led to the name Great Bear. The seven sages are Marici to the east (alpha), Vasishta (beta) to his west, then Angiras (gamma), then Atri (delta), then Pulastya (epsilon), then Pulaha (zeta), and Kratu (eta)” (5 and 6) : Brihat Samhita of Varahamihira. There are two sets of definitions as to who the saptha Rishi's are. The vedic tradition is 'Gautama, Vishwamithra, Jamahagni, Bharadwaaja, Kashyapa, Vasishtha and Athri' are the saptha rishis. However, the saptha Muni's according to Varahamihira are' Marichi, Vasishtha, Angirasa, Athri, Pulasthya, Pulaaha, and Kruthu'.
Thus 'Dhruva' clearly is Polaris. The saptha Rishi's are the seven major stars of Ursa major. 'Marichi' stands for Alkaid, 'Vasishta' stands for Mizar, 'Angirasa' stands for Alioth, 'Athri' stands for Megrez, 'Pulasthya' stands for Phecda, 'Pulaaha' stands for' Merak and 'Krathu' stands for DuBhe. The companion star for Mizar is Alcor. Hence 'Arundhathi' stands for Alcor. Vasishta and Arudhathi (Mizar-Alcor) can not be seen separate. The star Arundhathi is difficult to separate from Vasishta for people with poor eyesight.
Ancient astronomers are also called as rishis. Agasthya Rishi crossed vindhya mountains southwards and it is a major event in the vedic chrononlogy. A star in southern extreme is named after Agasthya or Canopus in constellation Carina.
There were many astronomers and many works have been lost. Few are discussed below:
- One of the earliest authors of Indian astrology, is said to be Pita Maha who wrote a treatise on astrology called Pita Maha Siddhant(a). He lived and wrote this book about 3,000 BCE.
- 2500 BCE another author-astrologer named Vashishtth(a) wrote several books on astrology, astronomy and philosophy. Vashishtth(a) Siddhant(a), but he wrote many other equally erudite and authoritative texts such as the Panch Siddhant(a) Kosh(a), Soory(a) Siddhant(a), Nityanand(a), Brhat Jatak(a), Aryabhat, Mansagari, Ranveer, and the Laghu Parashar.
- Aryabhata made contributions to Spherical geometry, a part of understanding the earth as a globe. Aryabhata had estimated the beginning of kaliyuga as 3102 BC. He stated that when he was 26, sixty of the 60-year cycles were completed after start of kaliyuga.
Aryabhata was the author of the Āryabhatīya and the Aryabhatasiddhanta. It is one of the earliest astronomical works to assign the start of each day to midnight. Aryabhata explicitly mentioned that the earth rotates about its axis, thereby causing what appears to be an apparent westward motion of the stars. Aryabhata also mentioned that reflected sunlight is the cause behind the shining of the moon. Ayrabhata's followers were particularly strong in South India, where his principles of the diurnal rotation of the earth, among others, were followed and a number of secondary works were based on them.
- Varaha Mihira's contributions include presently used Soorya Siddhanta, (He refers to nine types of time keeping and calenders) and the fact that he proposed Prime Meridian through Ujjain in Madhya Pradesh. He knew of Earth's Precession and called it as ayanaamsha. Varāhamihira was an astronomer and mathematician who studied and Indian astronomy as well as the many principles of Greek, Egyptian, and Roman astronomical sciences. His Pañcasiddhāntikā is a treatise and compendium drawing from several knowledge systems.
- Brahma Gupta made contributions to Arc sin in Trigonometry. Texts from that period like Yavana Jataka, Romaka Siddahnta provide evidence of understanding of European astronomical works. Brahmagupta reinforced Aryabhata's idea of another day beginning at midnight. Brahmagupta also calculated the instantaneous motion of a planet, gave correct equations for parallax, and some information related to the computation of eclipses. His works introduced Indian concept of mathematics based astronomy into the Arab world.
- Baskara authored the astronomical works Mahabhaskariya (Great Book of Bhaskara), Laghubhaskariya (Small Book of Bhaskara), and the Aryabhatiyabhashya (629 CE)—a commentary on the Āryabhatīya written by Aryabhata. Planetary longitudes, heliacal rising and setting of the planets, conjunctions among the planets and stars, solar and lunar eclipses, and the phases of the Moon are among the topics Bhaskara discusses in his astronomical treatises.
- Baskara I's works were followed by Vateśvara (880 CE), who in his eight chapter Vateśvarasiddhānta devised methods for determining the parallax in longitude directly, the motion of the equinoxes and the solstices, and the quadrant of the sun at any given time.
- Lalla 8th century CE Author of the Śisyadhīvrddhida (Treatise Which Expands the Intellect of Students), which corrects several assumptions of Āryabhata. Lalla also authored the Siddhāntatilaka.
- Bhāskara II 1114 CE Authored Siddhāntaśiromaṇi (Head Jewel of Accuracy) and Karaṇakutūhala (Calculation of Astronomical Wonders) and reported on his observations of planetary positions, conjunctions, eclipses, cosmography, geography, mathematics, and astronomical equipment used in his research at the observatory in Ujjain, which he headed.
- Śrīpati was an astronomer and mathematician who followed the Brhmagupta school and authored the Siddhāntaśekhara (The Crest of Established Doctrines) in 20 chapters, thereby introducing several new concepts, including moon's second inequlity.
- Mahendra Suri 14th century CE authored the Yantra-rāja (The King of Instruments, written in 1370 CE)—a Sanskrit work on the astrolabe, itself introduced in India during the reign of the 14th century
- In 1500, Nilakanthan Somayaji of the Kerala school of astronomy and mathematics, in his Tantrasangraha, revised Aryabhata's model for the planets Mercury and Venus.
- Acyuta Pisārati 1550–1621 CE
Sphutanirnaya (Determination of True Planets) details an elliptical correction to existing notions. Another work, Karanottama deals with eclipses, complementary relationship between the sun and the moon, and 'the derivation of the mean and true planets'.