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Saturday, September 15, 2018

Jainism and non-creationism

From Wikipedia, the free encyclopedia
 
Jainism does not support belief in a creator deity. According to Jain doctrine, the universe and its constituents—soul, matter, space, time, and principles of motion—have always existed. All the constituents and actions are governed by universal natural laws. It is not possible to create matter out of nothing and hence the sum total of matter in the universe remains the same (similar to law of conservation of mass). Jain text claims that the universe consists of jiva (life force or souls) and ajiva (lifeless objects). The soul of each living being is unique and uncreated and has existed since beginningless time.

The Jain theory of causation holds that a cause and its effect are always identical in nature and hence a conscious and immaterial entity like God cannot create a material entity like the universe. Furthermore, according to the Jain concept of divinity, any soul who destroys its karmas and desires achieves liberation (nirvana). A soul who destroys all its passions and desires has no desire to interfere in the working of the universe. Moral rewards and sufferings are not the work of a divine being, but a result of an innate moral order in the cosmos; a self-regulating mechanism whereby the individual reaps the fruits of his own actions through the workings of the karmas.

Through the ages, Jain philosophers have rejected and opposed the concept of creator and omnipotent God and this has resulted in Jainism being labeled as nastika darsana or atheist philosophy by the rival religious philosophies. The theme of non-creationism and absence of omnipotent God and divine grace runs strongly in all the philosophical dimensions of Jainism, including its cosmology, karma, moksa and its moral code of conduct. Jainism asserts a religious and virtuous life is possible without the idea of a creator god.

Jaina conception of the Universe

Representation of Universe in Jain cosmology in form of a lokapurusa or cosmic man.
Structure of Universe as per the Jain Scriptures.
 
Jain scriptures reject God as the creator of universe. Jainism offers an elaborate cosmology, including Heavenly beings/Devas. These Heavenly beings are not viewed as creators, they are subject to suffering and change like all other living beings, and must eventually die. If godliness is defined as the state of having freed one's soul from karmas and the attainment of enlightenment/Nirvana and a God as one who exists in such a state, then those who have achieved such a state can be termed Gods/Tirthankara. Thus, Mahavira was God/Tirthankara.

According to Jains, this loka or universe is an entity, always existing in varying forms with no beginning or end. Jain texts describe the shape of the universe as similar to a man standing with legs apart and arms resting on his waist. Thus, the universe is narrow at top, widens above the middle, narrows towards the middle, and once again becomes broad at the bottom.

Wheel of time

Jain Cosmic Wheel of Time

According to Jainism, time is beginningless and eternal. The cosmic wheel of time rotates ceaselessly. This cyclic nature eliminates the need for a creator, destroyer or external deity to maintain the universe.

The wheel of time is divided into two half-rotations, Utsarpiṇī or ascending time cycle and Avasarpiṇī, the descending time cycle, occurring continuously after each other. Utsarpiṇī is a period of progressive prosperity and happiness where the time spans and ages are at an increasing scale, while Avsarpiṇī is a period of increasing sorrow and immorality.

Concept of reality

This universe is made up of what Jainas call the six dravyas or substances classified as follows –
  • Jīva - The living substances
Jains believe that souls (Jīva) exist as a reality, with a separate existence from the body that houses it. It is characterised by cetana (consciousness) and upayoga (knowledge and perception). Though the soul experiences both birth and death, it is neither destroyed nor created. Decay and origin refer respectively to the disappearance of one state of soul and appearance of another, both merely various modes of the soul.
  • Ajīva - Non-Living Substances
    • Pudgala or Matter - Matter is solid, liquid, gas, energy, fine karmic materials and extra-fine matter or ultimate particles. Paramānu or ultimate particles are the basic building block of matter. One quality of paramānu and pudgala is permanence and indestructibility. It combines and changes its modes but its qualities remain the same. According to Jainism, it cannot be created nor destroyed.
    • Dharma-tattva or Medium of Motion and Adharma-tattva or Medium of Rest - Also known as Dharmāstikāya and Adharmāstikāya, they are distinct to Jain thought depicting motion and rest. They pervade the entire universe. Dharma-tattva and Adharma-tattva are by itself not motion or rest but mediate motion and rest in other bodies. Without dharmāstikāya motion is impossible and without adharmāstikāya rest is impossible in the Universe.
    • Ākāśa or Space - Space is a substance that accommodates living souls, matter, the principles of motion and rest, and time. It is all-pervading, infinite and made of infinite space-points.
    • Kāla or Time - Time is a real entity according to Jainism and all activities, changes or modifications are achieved only in time. Time is like a wheel with twelve spokes divided into descending and ascending: half with six stages of immense durations, each estimated at billions of "ocean years" (sagaropama). In each descending stage, sorrow increases and at each ascending stage, happiness and bliss increase.
These uncreated constituents of the universe impart dynamics upon the universe by interacting with each other. These constituents behave according to natural laws without interference from external entities. Dharma or true religion according to Jainism is vatthu sahāvo dhammo translated as "the intrinsic nature of a substance is its true dharma." 

Material cause and effect

According to Jainism, causes are of two types – Upādanā kārana (substantial or material cause) and Nimitta kārana (instrumental cause). Upādanā kārana is always identical with its effect. For example, out of clay, you can only produce a clay pot; hence the clay is the upādanā kārana or material cause and clay pot its effect. Wherever the effect is present, the cause is present and vice versa. The effect is always present in latent form in the material cause. For transforming the clay to pot, the potter, the wheel, the stick and other operating agents are required that are merely nimitta or instrumental cause or catalysts in transformation. The material cause always remains the clay. Hence the cause and effect are always entirely identical in nature.  Potter cannot be the material cause of pot. If this were the case, then Potter might as well prepare the pot without any clay. But this is not so. Thus a clay pot can only be made from clay; gold ornaments can be made only from gold. Similarly the different modes of existence of a soul are a result of activities of soul itself. There cannot be any contradiction or exceptions.

In such a scenario, Jains argue that the material cause of a living soul with cetana (conscious entity) is always the soul itself and cause of dead inert matter (non-cetana i.e. without any consciousness) is always the matter itself. If God is indeed the creator, then this is an impossible predication as the same cause will be responsible for two contradictory effects of cetana (life) and acetana (matter). This logically precludes an immaterial God (a conscious entity) from creating this Universe, which is made up of material substances.

The soul

According to Jainism, Soul is the master of its own destiny. One of the qualities of the soul is complete lordship of its own destiny. The soul alone chooses its actions and soul alone reaps its consequences. No God or prophet or angel can interfere in the actions or the destiny of the soul. Furthermore, it is the soul alone who makes the necessary efforts to achieve liberation without any divine grace.

Jains frequently assert that “we are alone” in this world. Amongst the Twelve Contemplations (anupreksas) of Jains, one of them is the loneliness of one's soul and nature of the universe and transmigration. Hence only by cleansing our soul by our own actions can we help ourselves.

Jainism thus lays a strong emphasis on the efforts and the freewill of the soul to achieve the desired goal of liberation.

Jaina conception of divinity

Image of a Siddha: the soul who attains Moksa; although the Siddhas (the liberated beings) are formless and without a body, this is how the Jain temples often depict the Siddhas.

According to Jainism, gods can be categorized into Tīrthankaras, Arihants or ordinary Kevalins and Siddhas. Jainism considers the Devīs and Devas to be celestial beings who dwell in heavens owing to meritorious deeds in their past lives.

Arhats

Arihants, also known as Kevalins, are "Gods" (supreme souls) in embodied states who ultimately become Siddhas, or liberated souls, at the time of their nirvana. An Arihant is a soul who has destroyed all passions, is totally unattached and without any desire and hence has destroyed the four ghātiyā karmas and attain kevala Jñāna, or omniscience. Such a soul still has a body and four aghātiyā karmas. An Arhata, at the end of his lifespan, destroys his remaining aghātiyā karma and becomes a Siddha.

Tīrthankaras

Tīrthankaras (also known as "Jinas") are Arihants who are teachers and revivers of the Jain philosophy. There are 24 Tīrthankaras in each time cycle; Mahāvīra was the 24th and last Tīrthankara of the current time cycle. Tīrthankaras are literally the ford makers who have shown the way to cross the ocean of rebirth and transmigration and hence have become a focus of reverence and worship amongst Jains. However it would be a mistake to regard the Tīrthankaras as gods analogous to the gods of Hindu pantheon despite the superficial resemblances in Jain and Hindu way of worship. Tīrthankaras like Arhatas ultimately become Siddhas on liberation. Tīrthankaras, being liberated, are beyond any kind of transactions with the rest of the universe. They are not the beings who exercise any sort of creative activity or who have the capacity or ability to intervene in answers to prayers.

Siddhas

 
Ultimately all Arihants and Tīrthankaras become Siddhas. A Siddha is a soul who is permanently liberated from the transmigratory cycle of birth and death. Such a soul, having realized its true self, is free from all the Karmas and embodiment. They are formless and dwell in Siddhashila (the realm of the liberated beings) at the apex of the universe in infinite bliss, infinite perception, infinite knowledge and infinite energy. Siddhahood is the ultimate goal of all souls.

Jains pray to these passionless Gods not for any favours or rewards but rather pray to the qualities of the God with the objective of destroying the karmas and achieving the Godhood. This is best understood by the term – vandetadgunalabhdhaye i.e. we pray to the attributes of such Gods to acquire such attributes” 

Heavenly beings – Demi-gods and demi-goddesses

Jainism describes existence of śāsanadevatās and śāsanadevīs, the attendant Gods and Goddesses of Tīrthankaras, who create the samavasarana or the divine preaching assembly of a Tīrthankara.


Worship of such gods is considered as mithyātva or wrong belief leading to bondage of karmas. However, many Jains are known to worship to such gods for material gains.

Nature of Karmas

According to Robert Zydendos, karma in Jainism can be considered a kind of system of laws, but natural rather than moral laws. In Jainism, actions that carry moral significance are considered to cause certain consequences in just the same way as, for instance, physical actions that do not carry any special moral significance. When one holds an apple in one's hand and then let go of the apple, the apple will fall: this is only natural. There is no judge, and no moral judgment involved, since this is a mechanical consequence of the physical action.

Hence in accordance with the natural karmic laws, consequences occur when one utters a lie, steals something, commits acts of senseless violence or leads the life of a debauchee. Rather than assume that moral rewards and retribution are the work of a divine judge, the Jains believe that there is an innate moral order to the cosmos, self-regulating through the workings of karma. Morality and ethics are important, not because of the personal whim of a fictional god, but because a life that is led in agreement with moral and ethical principles is beneficial: it leads to a decrease and finally to the total loss of karma, which means: to ever increasing happiness.

Karmas are often wrongly interpreted as a method for reward and punishment of a soul for its good and bad deeds. In Jainism, there is no question of there being any reward or punishment, as each soul is the master of its own destiny. The karmas can be said to represent a sum total of all unfulfilled desires of a soul. They enable the soul to experience the various themes of the lives that it desires to experience. They ultimately mature when the necessary supportive conditions required for maturity are fulfilled. Hence a soul may transmigrate from one life form to another for countless of years, taking with it the karmas that it has earned, until it finds conditions that bring about the fruits.

Hence whatever suffering or pleasure that a soul may be experiencing now is on account of choices that it has made in past. That is why Jainism stresses pure thinking and moral behavior. Apart from Buddhism, perhaps Jainism is the only religion that does not invoke the fear of God as a reason for moral behavior.

The karmic theory in Jainism operates endogenously. Tirthankaras are not attributed "absolute godhood" under Jainism. Thus, even the Tirthankaras themselves have to go through the stages of emanicipation, for attaining that state. While Buddhism does give a similar and to some extent a matching account for Shri Gautama Buddha, Hinduism maintains a totally different theory where "divine grace" is needed for emanicipation.

The following quote in Bhagavatī Ārādhanā (1616) sums up the predominance of karmas in Jain doctrine:


Thus it is not the so-called all embracing omnipotent God, but the law of karma that is the all governing force responsible for the manifest differences in the status, attainments and happiness of all life forms. It operates as a self-sustaining mechanism as natural universal law, without any need of an external entity to manage them.

Jain opposition to creationism

Jain scriptures reject God as the creator of universe. 12th century Ācārya Hemacandra puts forth the Jain view of universe in the Yogaśāstra as thus


Besides scriptural authority, Jains also resorted to syllogism and deductive reasoning to refute the creationist theories. Various views on divinity and universe held by the vedics, sāmkhyas, mimimsas, Buddhists and other school of thoughts were analysed, debated and repudiated by the various Jain Ācāryas. However the most eloquent refutation of this view is provided by Ācārya Jinasena in Mahāpurāna as thus

Criticisms of Jain non-creationist theory

Jainism along with Buddhism has been categorized as atheist philosophy i.e. Nāstika darśana by the followers of Vedic religion. However, the word Nāstika corresponds more to heterodox rather than atheism. Accordingly, those who did not believe in Vedas and rejected Brahma as the creator of Universe were labeled as Nāstika.

Mrs. Sinclair Stevenson, an Irish missionary, declared that “the heart of Jainism is empty” since it does not depend on beseeching an omnipotent God for salvation. While fervently appealing to accept Christianity, she says Jains believe strongly in forgiving others, and yet have no hope of forgiveness by a higher power. Jains believe that liberation is by personal effort not an appeal for divine intervention. “The Heart of Jainism” was written from her missionary point of view without respecting Jain sensibilities.

If atheism is defined as disbelief in existence of a God, then Jainism cannot be labeled as atheistic, as it not only believes in existence of gods but also of the soul which can attain godhood. As Paul Dundas puts it – “while Jainism is, as we have seen, atheist in a limited sense of rejection of both the existence of a creator God and the possibility of intervention of such a being in human affairs, it nonetheless must be regarded as a theist religion in the more profound sense that it accepts the existence of divine principle, the paramātmā i.e. God, existing in potential state within all beings”.

The Jaina position on God and religion from a perspective of a non-Jain can be summed up in the words of Anne Vallely.

History of astronomy

From Wikipedia, the free encyclopedia
 
A star map with a cylindrical projection. Su Song's star maps represent the oldest existent ones in printed form.

Astronomy is the oldest of the natural sciences, dating back to antiquity, with its origins in the religious, mythological, cosmological, calendrical, and astrological beliefs and practices of prehistory: vestiges of these are still found in astrology, a discipline long interwoven with public and governmental astronomy. It was not completely separated in Europe during the Copernican Revolution starting in 1543. In some cultures, astronomical data was used for astrological prognostication.

Ancient astronomers were able to differentiate between stars and planets, as stars remain relatively fixed over the centuries while planets will move an appreciable amount during a comparatively short time.

Early history

Early cultures identified celestial objects with gods and spirits. They related these objects (and their movements) to phenomena such as rain, drought, seasons, and tides. It is generally believed that the first astronomers were priests, and that they understood celestial objects and events to be manifestations of the divine, hence early astronomy's connection to what is now called astrology. Ancient structures with possibly astronomical alignments (such as Stonehenge) probably fulfilled astronomical, religious, and social functions.

Calendars of the world have often been set by observations of the Sun and Moon (marking the day, month and year), and were important to agricultural societies, in which the harvest depended on planting at the correct time of year, and for which the nearly full moon was the only lighting for night-time travel into city markets.

sunset at the equinox from the prehistoric site of Pizzo Vento at Fondachelli Fantina, Sicily

The common modern calendar is based on the Roman calendar. Although originally a lunar calendar, it broke the traditional link of the month to the phases of the moon and divided the year into twelve almost-equal months, that mostly alternated between thirty and thirty-one days. Julius Caesar instigated calendar reform in 46 BCE and introduced what is now called the Julian calendar, based upon the 365 ​14 day year length originally proposed by the 4th century BCE Greek astronomer Callippus.

Prehistoric Europe

The Nebra sky disk Germany 1600 BC
 
Calendrical functions of the Berlin Gold Hat c. 1000 BC
 
Since 1990 our understanding of prehistoric Europeans has been radically changed by discoveries of ancient astronomical artifacts throughout Europe. The artifacts demonstrate that Neolithic and Bronze Age Europeans had a sophisticated knowledge of mathematics and astronomy.
Among the discoveries are:
  • Bone sticks from locations like Africa and Europe from possibly as long ago as 35,000 BCE are marked in ways that tracked the moon's phases.
  • The Warren Field calendar in the Dee River valley of Scotland's Aberdeenshire. First excavated in 2004 but only in 2013 revealed as a find of huge significance, it is to date the world´s oldest known calendar, created around 8000 BC and predating all other calendars by some 5,000 years. The calendar takes the form of an early Mesolithic monument containing a series of 12 pits which appear to help the observer track lunar months by mimicking the phases of the moon. It also aligns to sunrise at the winter solstice, thus coordinating the solar year with the lunar cycles. The monument had been maintained and periodically reshaped, perhaps up to hundreds of times, in response to shifting solar/lunar cycles, over the course of 6,000 years, until the calendar fell out of use around 4,000 years ago.
  • Goseck circle is located in Germany and belongs to the linear pottery culture. First discovered in 1991, its significance was only clear after results from archaeological digs became available in 2004. The site is one of hundreds of similar circular enclosures built in a region encompassing Austria, Germany, and the Czech Republic during a 200-year period starting shortly after 5000 BC.
  • The Nebra sky disc is a Bronze Age bronze disc that was buried in Germany, not far from the Goseck circle, around 1600 BC. It measures about 30 cm diameter with a mass of 2.2 kg and displays a blue-green patina (from oxidization) inlaid with gold symbols. Found by archeological thieves in 1999 and recovered in Switzerland in 2002, it was soon recognized as a spectacular discovery, among the most important of the 20th century. Investigations revealed that the object had been in use around 400 years before burial (2000 BC), but that its use had been forgotten by the time of burial. The inlaid gold depicted the full moon, a crescent moon about 4 or 5 days old, and the Pleiades star cluster in a specific arrangement forming the earliest known depiction of celestial phenomena. Twelve lunar months pass in 354 days, requiring a calendar to insert a leap month every two or three years in order to keep synchronized with the solar year's seasons (making it lunisolar). The earliest known descriptions of this coordination were recorded by the Babylonians in 6th or 7th centuries BC, over one thousand years later. Those descriptions verified ancient knowledge of the Nebra sky disc's celestial depiction as the precise arrangement needed to judge when to insert the intercalary month into a lunisolar calendar, making it an astronomical clock for regulating such a calendar a thousand or more years before any other known method.
  • The Kokino site, discovered in 2001, sits atop an extinct volcanic cone at an elevation of 1,013 metres (3,323 ft), occupying about 0.5 hectares overlooking the surrounding countryside in Macedonia. A Bronze Age astronomical observatory was constructed there around 1900 BC and continuously served the nearby community that lived there until about 700 BC. The central space was used to observe the rising of the sun and full moon. Three markings locate sunrise at the summer and winter solstices and at the two equinoxes. Four more give the minimum and maximum declinations of the full moon: in summer, and in winter. Two measure the lengths of lunar months. Together, they reconcile solar and lunar cycles in marking the 235 lunations that occur during 19 solar years, regulating a lunar calendar. On a platform separate from the central space, at lower elevation, four stone seats (thrones) were made in north-south alignment, together with a trench marker cut in the eastern wall. This marker allows the rising sun's light to fall on only the second throne, at midsummer (about July 31). It was used for ritual ceremony linking the ruler to the local sun god, and also marked the end of the growing season and time for harvest.
  • Golden hats of Germany, France and Switzerland dating from 1400-800 BC are associated with the Bronze Age Urnfield culture. The Golden hats are decorated with a spiral motif of the Sun and the Moon. They were probably a kind of calendar used to calibrate between the lunar and solar calendars. Modern scholarship has demonstrated that the ornamentation of the gold leaf cones of the Schifferstadt type, to which the Berlin Gold Hat example belongs, represent systematic sequences in terms of number and types of ornaments per band. A detailed study of the Berlin example, which is the only fully preserved one, showed that the symbols probably represent a lunisolar calendar. The object would have permitted the determination of dates or periods in both lunar and solar calendars.

Ancient times

Mesopotamia

Babylonian tablet recording Halley's comet in 164 BC.

The origins of Western astronomy can be found in Mesopotamia, the "land between the rivers" Tigris and Euphrates, where the ancient kingdoms of Sumer, Assyria, and Babylonia were located. A form of writing known as cuneiform emerged among the Sumerians around 3500–3000 BC. Our knowledge of Sumerian astronomy is indirect, via the earliest Babylonian star catalogues dating from about 1200 BC. The fact that many star names appear in Sumerian suggests a continuity reaching into the Early Bronze Age. Astral theology, which gave planetary gods an important role in Mesopotamian mythology and religion, began with the Sumerians. They also used a sexagesimal (base 60) place-value number system, which simplified the task of recording very large and very small numbers. The modern practice of dividing a circle into 360 degrees, or an hour into 60 minutes, began with the Sumerians. For more information, see the articles on Babylonian numerals and mathematics.

Classical sources frequently use the term Chaldeans for the astronomers of Mesopotamia, who were, in reality, priest-scribes specializing in astrology and other forms of divination.

The first evidence of recognition that astronomical phenomena are periodic and of the application of mathematics to their prediction is Babylonian. Tablets dating back to the Old Babylonian period document the application of mathematics to the variation in the length of daylight over a solar year. Centuries of Babylonian observations of celestial phenomena are recorded in the series of cuneiform tablets known as the Enūma Anu Enlil. The oldest significant astronomical text that we possess is Tablet 63 of the Enūma Anu Enlil, the Venus tablet of Ammi-saduqa, which lists the first and last visible risings of Venus over a period of about 21 years and is the earliest evidence that the phenomena of a planet were recognized as periodic. The MUL.APIN, contains catalogues of stars and constellations as well as schemes for predicting heliacal risings and the settings of the planets, lengths of daylight measured by a water clock, gnomon, shadows, and intercalations. The Babylonian GU text arranges stars in 'strings' that lie along declination circles and thus measure right-ascensions or time-intervals, and also employs the stars of the zenith, which are also separated by given right-ascensional differences.

A significant increase in the quality and frequency of Babylonian observations appeared during the reign of Nabonassar (747–733 BC). The systematic records of ominous phenomena in Babylonian astronomical diaries that began at this time allowed for the discovery of a repeating 18-year cycle of lunar eclipses, for example. The Greek astronomer Ptolemy later used Nabonassar's reign to fix the beginning of an era, since he felt that the earliest usable observations began at this time.

The last stages in the development of Babylonian astronomy took place during the time of the Seleucid Empire (323–60 BC). In the 3rd century BC, astronomers began to use "goal-year texts" to predict the motions of the planets. These texts compiled records of past observations to find repeating occurrences of ominous phenomena for each planet. About the same time, or shortly afterwards, astronomers created mathematical models that allowed them to predict these phenomena directly, without consulting past records. A notable Babylonian astronomer from this time was Seleucus of Seleucia, who was a supporter of the heliocentric model.

Babylonian astronomy was the basis for much of what was done in Greek and Hellenistic astronomy, in classical Indian astronomy, in Sassanian Iran, in Byzantium, in Syria, in Islamic astronomy, in Central Asia, and in Western Europe.

India

Historical Jantar Mantar observatory in Jaipur, India.

Astronomy in the Indian subcontinent dates back to the period of Indus Valley Civilization during 3rd millennium BCE, when it was used to create calendars. As the Indus Valley civilization did not leave behind written documents, the oldest extant Indian astronomical text is the Vedanga Jyotisha, dating from the Vedic period. Vedanga Jyotisha describes rules for tracking the motions of the Sun and the Moon for the purposes of ritual. During the 6th century, astronomy was influenced by the Greek and Byzantine astronomical traditions.

Aryabhata (476–550), in his magnum opus Aryabhatiya (499), propounded a computational system based on a planetary 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 Sun. He accurately calculated many astronomical constants, such as the periods of the planets, times of the solar and lunar eclipses, and the instantaneous motion of the Moon. Early followers of Aryabhata's model included Varahamihira, Brahmagupta, and Bhaskara II.

Astronomy was advanced during the Shunga Empire and many star catalogues were produced during this time. The Shunga period is known as the "Golden age of astronomy in India". It saw the development of calculations for the motions and places of various planets, their rising and setting, conjunctions, and the calculation of eclipses.

Indian astronomers by the 6th century believed that comets were celestial bodies that re-appeared periodically. This was the view expressed in the 6th century by the astronomers Varahamihira and Bhadrabahu, and the 10th-century astronomer Bhattotpala listed the names and estimated periods of certain comets, but it is unfortunately not known how these figures were calculated or how accurate they were.

Bhāskara II (1114–1185) was the head of the astronomical observatory at Ujjain, continuing the mathematical tradition of Brahmagupta. He wrote the Siddhantasiromani which consists of two parts: Goladhyaya (sphere) and Grahaganita (mathematics of the planets). He also calculated the time taken for the Earth to orbit the sun to 9 decimal places. The Buddhist University of Nalanda at the time offered formal courses in astronomical studies.

Other important astronomers from India include Madhava of Sangamagrama, Nilakantha Somayaji and Jyeshtadeva, who were members of the Kerala school of astronomy and mathematics from the 14th century to the 16th century. Nilakantha Somayaji, in his Aryabhatiyabhasya, a commentary on Aryabhata's Aryabhatiya, developed his own 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. Nilakantha's system, however, was mathematically more efficient than the Tychonic system, due to correctly taking into account the equation of the centre and latitudinal motion of Mercury and Venus. Most astronomers of the Kerala school of astronomy and mathematics who followed him accepted his planetary model.

Greece and Hellenistic world

The Antikythera Mechanism was an analog computer from 150–100 BC designed to calculate the positions of astronomical objects.

The Ancient Greeks developed astronomy, which they treated as a branch of mathematics, to a highly sophisticated level. The first geometrical, three-dimensional models to explain the apparent motion of the planets were developed in the 4th century BC by Eudoxus of Cnidus and Callippus of Cyzicus. Their models were based on nested homocentric spheres centered upon the Earth. Their younger contemporary Heraclides Ponticus proposed that the Earth rotates around its axis.

A different approach to celestial phenomena was taken by natural philosophers such as Plato and Aristotle. They were less concerned with developing mathematical predictive models than with developing an explanation of the reasons for the motions of the Cosmos. In his Timaeus, Plato described the universe as a spherical body divided into circles carrying the planets and governed according to harmonic intervals by a world soul. Aristotle, drawing on the mathematical model of Eudoxus, proposed that the universe was made of a complex system of concentric spheres, whose circular motions combined to carry the planets around the earth. This basic cosmological model prevailed, in various forms, until the 16th century.

In the 3rd century BC Aristarchus of Samos was the first to suggest a heliocentric system, although only fragmentary descriptions of his idea survive. Eratosthenes, using the angles of shadows created at widely separated regions, estimated the circumference of the Earth with great accuracy.

Greek geometrical astronomy developed away from the model of concentric spheres to employ more complex models in which an eccentric circle would carry around a smaller circle, called an epicycle which in turn carried around a planet. The first such model is attributed to Apollonius of Perga and further developments in it were carried out in the 2nd century BC by Hipparchus of Nicea. Hipparchus made a number of other contributions, including the first measurement of precession and the compilation of the first star catalog in which he proposed our modern system of apparent magnitudes.

The Antikythera mechanism, an ancient Greek astronomical observational device for calculating the movements of the Sun and the Moon, possibly the planets, dates from about 150–100 BC, and was the first ancestor of an astronomical computer. It was discovered in an ancient shipwreck off the Greek island of Antikythera, between Kythera and Crete. The device became famous for its use of a differential gear, previously believed to have been invented in the 16th century, and the miniaturization and complexity of its parts, comparable to a clock made in the 18th century. The original mechanism is displayed in the Bronze collection of the National Archaeological Museum of Athens, accompanied by a replica.

Depending on the historian's viewpoint, the acme or corruption of physical Greek astronomy is seen with Ptolemy of Alexandria, who wrote the classic comprehensive presentation of geocentric astronomy, the Megale Syntaxis (Great Synthesis), better known by its Arabic title Almagest, which had a lasting effect on astronomy up to the Renaissance. In his Planetary Hypotheses, Ptolemy ventured into the realm of cosmology, developing a physical model of his geometric system, in a universe many times smaller than the more realistic conception of Aristarchus of Samos four centuries earlier.

Egypt

 
The precise orientation of the Egyptian pyramids affords a lasting demonstration of the high degree of technical skill in watching the heavens attained in the 3rd millennium BC. It has been shown the Pyramids were aligned towards the pole star, which, because of the precession of the equinoxes, was at that time Thuban, a faint star in the constellation of Draco. Evaluation of the site of the temple of Amun-Re at Karnak, taking into account the change over time of the obliquity of the ecliptic, has shown that the Great Temple was aligned on the rising of the midwinter sun. The length of the corridor down which sunlight would travel would have limited illumination at other times of the year.

Astronomy played a considerable part in religious matters for fixing the dates of festivals and determining the hours of the night. The titles of several temple books are preserved recording the movements and phases of the sun, moon and stars. The rising of Sirius (Egyptian: Sopdet, Greek: Sothis) at the beginning of the inundation was a particularly important point to fix in the yearly calendar.

Writing in the Roman era, Clement of Alexandria gives some idea of the importance of astronomical observations to the sacred rites:
And after the Singer advances the Astrologer (ὡροσκόπος), with a horologium (ὡρολόγιον) in his hand, and a palm (φοίνιξ), the symbols of astrology. He must know by heart the Hermetic astrological books, which are four in number. Of these, one is about the arrangement of the fixed stars that are visible; one on the positions of the sun and moon and five planets; one on the conjunctions and phases of the sun and moon; and one concerns their risings.
The Astrologer's instruments (horologium and palm) are a plumb line and sighting instrument. They have been identified with two inscribed objects in the Berlin Museum; a short handle from which a plumb line was hung, and a palm branch with a sight-slit in the broader end. The latter was held close to the eye, the former in the other hand, perhaps at arms length. The "Hermetic" books which Clement refers to are the Egyptian theological texts, which probably have nothing to do with Hellenistic Hermetism.

From the tables of stars on the ceiling of the tombs of Rameses VI and Rameses IX it seems that for fixing the hours of the night a man seated on the ground faced the Astrologer in such a position that the line of observation of the pole star passed over the middle of his head. On the different days of the year each hour was determined by a fixed star culminating or nearly culminating in it, and the position of these stars at the time is given in the tables as in the centre, on the left eye, on the right shoulder, etc. According to the texts, in founding or rebuilding temples the north axis was determined by the same apparatus, and we may conclude that it was the usual one for astronomical observations. In careful hands it might give results of a high degree of accuracy.

China

Printed star map of Su Song (1020–1101) showing the south polar projection.

The astronomy of East Asia began in China. Solar term was completed in Warring States period. The knowledge of Chinese astronomy was introduced into East Asia.

Astronomy in China has a long history. Detailed records of astronomical observations were kept from about the 6th century BC, until the introduction of Western astronomy and the telescope in the 17th century. Chinese astronomers were able to precisely predict eclipses.

Much of early Chinese astronomy was for the purpose of timekeeping. The Chinese used a lunisolar calendar, but because the cycles of the Sun and the Moon are different, astronomers often prepared new calendars and made observations for that purpose.

Astrological divination was also an important part of astronomy. Astronomers took careful note of "guest stars" which suddenly appeared among the fixed stars. They were the first to record a supernova, in the Astrological Annals of the Houhanshu in 185 AD. Also, the supernova that created the Crab Nebula in 1054 is an example of a "guest star" observed by Chinese astronomers, although it was not recorded by their European contemporaries. Ancient astronomical records of phenomena like supernovae and comets are sometimes used in modern astronomical studies.

The world's first star catalogue was made by Gan De, a Chinese astronomer, in the 4th century BC.

Mesoamerica

"El Caracol" observatory temple at Chichen Itza, Mexico.

Maya astronomical codices include detailed tables for calculating phases of the Moon, the recurrence of eclipses, and the appearance and disappearance of Venus as morning and evening star. The Maya based their calendrics in the carefully calculated cycles of the Pleiades, the Sun, the Moon, Venus, Jupiter, Saturn, Mars, and also they had a precise description of the eclipses as depicted in the Dresden Codex, as well as the ecliptic or zodiac, and the Milky Way was crucial in their Cosmology. A number of important Maya structures are believed to have been oriented toward the extreme risings and settings of Venus. To the ancient Maya, Venus was the patron of war and many recorded battles are believed to have been timed to the motions of this planet. Mars is also mentioned in preserved astronomical codices and early mythology.

Although the Maya calendar was not tied to the Sun, John Teeple has proposed that the Maya calculated the solar year to somewhat greater accuracy than the Gregorian calendar. Both astronomy and an intricate numerological scheme for the measurement of time were vitally important components of Maya religion.

Medieval Middle East

Arabic astrolabe from 1208 AD

The Arabic and the Persian world under Islam had become highly cultured, and many important works of knowledge from Greek astronomy and Indian astronomy and Persian astronomy were translated into Arabic, used and stored in libraries throughout the area. An important contribution by Islamic astronomers was their emphasis on observational astronomy. This led to the emergence of the first astronomical observatories in the Muslim world by the early 9th century. Zij star catalogues were produced at these observatories.

In the 10th century, Abd al-Rahman al-Sufi (Azophi) carried out observations on the stars and described their positions, magnitudes, brightness, and colour and drawings for each constellation in his Book of Fixed Stars. He also gave the first descriptions and pictures of "A Little Cloud" now known as the Andromeda Galaxy. He mentions it as lying before the mouth of a Big Fish, an Arabic constellation. This "cloud" was apparently commonly known to the Isfahan astronomers, very probably before 905 AD. The first recorded mention of the Large Magellanic Cloud was also given by al-Sufi. In 1006, Ali ibn Ridwan observed SN 1006, the brightest supernova in recorded history, and left a detailed description of the temporary star.

In the late 10th century, a huge observatory was built near Tehran, Iran, by the astronomer Abu-Mahmud al-Khujandi who observed a series of meridian transits of the Sun, which allowed him to calculate the tilt of the Earth's axis relative to the Sun. He noted that measurements by earlier (Indian, then Greek) astronomers had found higher values for this angle, possible evidence that the axial tilt is not constant but was in fact decreasing. In 11th-century Persia, Omar Khayyám compiled many tables and performed a reformation of the calendar that was more accurate than the Julian and came close to the Gregorian.

Other Muslim advances in astronomy included the collection and correction of previous astronomical data, resolving significant problems in the Ptolemaic model, the development of the universal latitude-independent astrolabe by Arzachel, the invention of numerous other astronomical instruments, Ja'far Muhammad ibn Mūsā ibn Shākir's belief that the heavenly bodies and celestial spheres were subject to the same physical laws as Earth, the first elaborate experiments related to astronomical phenomena, the introduction of exacting empirical observations and experimental techniques, and the introduction of empirical testing by Ibn al-Shatir, who produced the first model of lunar motion which matched physical observations.

Natural philosophy (particularly Aristotelian physics) was separated from astronomy by Ibn al-Haytham (Alhazen) in the 11th century, by Ibn al-Shatir in the 14th century, and Qushji in the 15th century, leading to the development of an astronomical physics.

Medieval Western Europe

9th-century diagram of the positions of the seven planets on 18 March 816.

After the significant contributions of Greek scholars to the development of astronomy, it entered a relatively static era in Western Europe from the Roman era through the 12th century. This lack of progress has led some astronomers to assert that nothing happened in Western European astronomy during the Middle Ages. Recent investigations, however, have revealed a more complex picture of the study and teaching of astronomy in the period from the 4th to the 16th centuries.

Western Europe entered the Middle Ages with great difficulties that affected the continent's intellectual production. The advanced astronomical treatises of classical antiquity were written in Greek, and with the decline of knowledge of that language, only simplified summaries and practical texts were available for study. The most influential writers to pass on this ancient tradition in Latin were Macrobius, Pliny, Martianus Capella, and Calcidius. In the 6th century Bishop Gregory of Tours noted that he had learned his astronomy from reading Martianus Capella, and went on to employ this rudimentary astronomy to describe a method by which monks could determine the time of prayer at night by watching the stars.

In the 7th century the English monk Bede of Jarrow published an influential text, On the Reckoning of Time, providing churchmen with the practical astronomical knowledge needed to compute the proper date of Easter using a procedure called the computus. This text remained an important element of the education of clergy from the 7th century until well after the rise of the Universities in the 12th century.

The range of surviving ancient Roman writings on astronomy and the teachings of Bede and his followers began to be studied in earnest during the revival of learning sponsored by the emperor Charlemagne. By the 9th century rudimentary techniques for calculating the position of the planets were circulating in Western Europe; medieval scholars recognized their flaws, but texts describing these techniques continued to be copied, reflecting an interest in the motions of the planets and in their astrological significance.

Building on this astronomical background, in the 10th century European scholars such as Gerbert of Aurillac began to travel to Spain and Sicily to seek out learning which they had heard existed in the Arabic-speaking world. There they first encountered various practical astronomical techniques concerning the calendar and timekeeping, most notably those dealing with the astrolabe. Soon scholars such as Hermann of Reichenau were writing texts in Latin on the uses and construction of the astrolabe and others, such as Walcher of Malvern, were using the astrolabe to observe the time of eclipses in order to test the validity of computistical tables.

By the 12th century, scholars were traveling to Spain and Sicily to seek out more advanced astronomical and astrological texts, which they translated into Latin from Arabic and Greek to further enrich the astronomical knowledge of Western Europe. The arrival of these new texts coincided with the rise of the universities in medieval Europe, in which they soon found a home. Reflecting the introduction of astronomy into the universities, John of Sacrobosco wrote a series of influential introductory astronomy textbooks: the Sphere, a Computus, a text on the Quadrant, and another on Calculation.

In the 14th century, Nicole Oresme, later bishop of Liseux, showed that neither the scriptural texts nor the physical arguments advanced against the movement of the Earth were demonstrative and adduced the argument of simplicity for the theory that the earth moves, and not the heavens. However, he concluded "everyone maintains, and I think myself, that the heavens do move and not the earth: For God hath established the world which shall not be moved." In the 15th century, cardinal Nicholas of Cusa suggested in some of his scientific writings that the Earth revolved around the Sun, and that each star is itself a distant sun. He was not, however, describing a scientifically verifiable theory of the universe.

Copernican Revolution

During the renaissance period, astronomy began to undergo a revolution in thought known as the Copernican revolution, which gets the name from the astronomer Nicolaus Copernicus, who proposed a heliocentric system, in which the planets revolved around the Sun and not the Earth. His De Revolutionibus Orbium Coelestium was published in 1543. While in the long term this was a very controversial claim, in the very beginning it only brought minor controversy. The theory became the dominant view because many figures, most notably Galileo Galilei, Johannes Kepler and Isaac Newton championed and improved upon the work. Other figures also aided this new model despite not believing the overall theory, like Tycho Brahe, with his well-known observations.

Brahe, a Danish noble, was an essential astronomer in this period. He came on the astronomical scene with the publication of De Nova Stella in which he disproved conventional wisdom on SN 1572. He also created the Tychonic System in which he blended the mathematical benefits of the Copernican system and the “physical benefits” of the Ptolemaic system. This was one of the systems people believed in when they did not accept heliocentrism, but could no longer accept the Ptolemaic system. He is most known for his highly accurate observations of the stars and the solar system. Later he moved to Prague and continued his work. In Prague he was at work on the Rudolphine Tables, that were not finished until after his death. The Rudolphine Tables was a star map designed to be more accurate than either the Alphonsine Tables, made in the 1300s and the Prutenic Tables which were inaccurate. He was assisted at this time by his assistant Johannes Kepler, who would later use his observations to finish Brahe’s works and for his theories as well.

After the death of Brahe, Kepler was deemed his successor and was given the job of complete Brahe’s uncompleted works, like the Rudolphine Tables. He completed the Rudolphine Tables in 1624, although it was not published for several years. Like many other figures of this era, he was subject to religious and political troubles, like the thirty-year war, which led to chaos that almost destroyed some of his works. Kepler was, however, the first to attempt to derive mathematical predictions of celestial motions from assumed physical causes. Kepler discovered the three laws of planetary motion that now carry his name. Those laws being as follows:
  1. The orbit of a planet is an ellipse with the Sun at one of the two foci.
  2. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
  3. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
With these laws, he managed to improve upon the existing Heliocentric model. The first two were published in 1609. Kepler's contributions improved upon the overall system, giving it more credibility because it adequately explained events and could cause more reliable predictions. Before this the Copernican model was just as unreliable as the ptolemaic model. This improvement came because Kepler realized the orbits were not perfect circles, but ellipses.

Galileo Galilei (1564–1642) crafted his own telescope and discovered that our Moon had craters, that Jupiter had moons, that the Sun had spots, and that Venus had phases like our Moon.

Galileo Galilei was among the first to use a telescope to observe the sky, and after constructing a 20x refractor telescope. He discovered the four largest moons of Jupiter in 1610, which are now collectively known as the Galilean moons, in his honor. This discovery was the first known observation of satellites orbiting another planet. He also found that our Moon had craters and observed, and correctly explained, sunspots, and that Venus exhibited a full set of phases resembling lunar phases. Galileo argued that these facts demonstrated incompatibility with the Ptolemaic model, which could not explain the phenomenon and would even contradict it. With the moons it demonstrated that the earth does not have to have everything orbiting it and that other parts of the solar system could orbit another object, such as the earth orbiting the sun. In ptolemaic system the celestial bodies were supposed to be perfect so such objects should not have craters or sunspots. The phases of venus could only happen in the event that venus orbit is insides earth's orbit which could not happen if the earth was the center. He, as the most famous example, had to faced challenges from church officials, more specifically the Roman Inquisition. They accused him of heresy because these beliefs went against the teachings of the Bible and was challenging the Catholic church's authority when it was at its weakest. While he was able to avoid punishment for a little while he was eventually tried and pled guilty to heresy in 1633. Although this came at some expense—his book was banned—and he was put under house arrest until he died in 1642.

Plate with figures illustrating articles on astronomy, from the 1728 Cyclopaedia

Isaac Newton developed further ties between physics and astronomy through his law of universal gravitation. Realizing that the same force that attracts objects to the surface of the Earth held the moon in orbit around the Earth, Newton was able to explain—in one theoretical framework—all known gravitational phenomena. In his Philosophiae Naturalis Principia Mathematica, he derived Kepler's laws from first principles. Those first principles are as follows:
  1. In an inertial frame of reference, an object either remains at rest or continues to move at constant velocity, unless acted upon by a force.
  2. In an inertial reference frame, the vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration a of the object: F = ma. (It is assumed here that the mass m is constant)
  3. When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
Thus while Kepler explained how the planets moved, Newton accurately managed to explain why the planets moved the way they do. Newton's theoretical developments laid many of the foundations of modern physics.

Completing the solar system

Outside of England, Newton's theory took some time to become established. Descartes' theory of vortices held sway in France, and Huygens, Leibniz and Cassini accepted only parts of Newton's system, preferring their own philosophies. Voltaire published a popular account in 1738. In 1748, the French Academy of Sciences offered a reward for solving the perturbations of Jupiter and Saturn which was eventually solved by Euler and Lagrange. Laplace completed the theory of the planets, publishing from 1798 to 1825.

Edmund Halley succeeded Flamsteed as Astronomer Royal in England and succeeded in predicting the return in 1758 of the comet that bears his name. Sir William Herschel found the first new planet, Uranus, to be observed in modern times in 1781. The gap between the planets Mars and Jupiter disclosed by the Titius–Bode law was filled by the discovery of the asteroids Ceres and Pallas in 1801 and 1802 with many more following.

At first, astronomical thought in America was based on Aristotelian philosophy, but interest in the new astronomy began to appear in Almanacs as early as 1659.

Modern astronomy

Mars surface map of Giovanni Schiaparelli.

In the 19th century it was discovered that (by Joseph von Fraunhofer), when sunlight was dispersed, a multitude of spectral lines were observed (regions where there was less or no light). Experiments with hot gases showed that the same lines could be observed in the spectra of gases, specific lines corresponding to unique elements. It was proved that the chemical elements found in the Sun (chiefly hydrogen and helium) were also found on Earth. During the 20th century spectroscopy (the study of these lines) advanced, especially because of the advent of quantum physics, that was necessary to understand the observations.

Although in previous centuries noted astronomers were exclusively male, at the turn of the 20th century women began to play a role in the great discoveries. In this period prior to modern computers, women at the United States Naval Observatory (USNO), Harvard University, and other astronomy research institutions began to be hired as human "computers," who performed the tedious calculations while scientists performed research requiring more background knowledge.  A number of discoveries in this period were originally noted by the women "computers" and reported to their supervisors. For example, at the Harvard Observatory Henrietta Swan Leavitt discovered the cepheid variable star period-luminosity relation which she further developed into a method of measuring distance outside of our solar system. Annie Jump Cannon, also at Harvard, organized the stellar spectral types according to stellar temperature. In 1847, Maria Mitchell discovered a comet using a telescope. According to Lewis D. Eigen, Cannon alone, "in only 4 years discovered and catalogued more stars than all the men in history put together." Most of these women received little or no recognition during their lives due to their lower professional standing in the field of astronomy. Although their discoveries and methods are taught in classrooms around the world, few students of astronomy can attribute the works to their authors or have any idea that there were active female astronomers at the end of the 19th century.

Cosmology and the expansion of the universe

Comparison of CMB (Cosmic microwave background) results from satellites COBE, WMAP and Planck documenting a progress in 1989-2013.

Most of our current knowledge was gained during the 20th century. With the help of the use of photography, fainter objects were observed. Our sun was found to be part of a galaxy made up of more than 1010 stars (10 billion stars). The existence of other galaxies, one of the matters of the great debate, was settled by Edwin Hubble, who identified the Andromeda nebula as a different galaxy, and many others at large distances and receding, moving away from our galaxy.

Physical cosmology, a discipline that has a large intersection with astronomy, made huge advances during the 20th century, with the model of the hot big bang heavily supported by the evidence provided by astronomy and physics, such as the redshifts of very distant galaxies and radio sources, the cosmic microwave background radiation, Hubble's law and cosmological abundances of elements.

New windows into the Cosmos open


In the 19th century, scientists began discovering forms of light which were invisible to the naked eye: X-Rays, gamma rays, radio waves, microwaves, ultraviolet radiation, and infrared radiation. This had a major impact on astronomy, spawning the fields of infrared astronomy, radio astronomy, x-ray astronomy and finally gamma-ray astronomy. With the advent of spectroscopy it was proven that other stars were similar to our own sun, but with a range of temperatures, masses and sizes. The existence of our galaxy, the Milky Way, as a separate group of stars was only proven in the 20th century, along with the existence of "external" galaxies, and soon after, the expansion of the universe seen in the recession of most galaxies from us. 

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