105-649: The Extrasolar Planets Encyclopaedia (also known as Encyclopaedia of exoplanetary systems and Catalogue of Exoplanets ) is an astronomy website , founded in Paris , France at the Meudon Observatory by Jean Schneider in February 1995, which maintains a database of all the currently known and candidate extrasolar planets , with individual pages for each planet and a full list interactive catalog spreadsheet. The main catalogue comprises databases of all of
210-448: A binary black hole . A second gravitational wave was detected on 26 December 2015 and additional observations should continue but gravitational waves require extremely sensitive instruments. The combination of observations made using electromagnetic radiation, neutrinos or gravitational waves and other complementary information, is known as multi-messenger astronomy . One of the oldest fields in astronomy, and in all of science,
315-483: A Greek origin for certain aspects of Indian astronomy. One of the direct proofs for this approach is the fact quoted that many Sanskrit words related to astronomy, astrology and calendar are either direct phonetical borrowings from the Greek language, or translations, assuming complex ideas, like the names of the days of the week which presuppose a relation between those days, planets (including Sun and Moon) and gods. With
420-673: A Persian treatise on astronomy. He wrote about the heliocentric model, and argued that there exists an infinite number of universes ( awalim ), each with their own planets and stars, and that this demonstrates the omnipotence of God, who is not confined to a single universe. The last known Zij treatise was the Zij-i Bahadurkhani , written in 1838 by the Indian astronomer Ghulam Hussain Jaunpuri (1760–1862) and printed in 1855, dedicated to Bahadur Khan . The treatise incorporated
525-562: A few milliseconds to thousands of seconds before fading away. Only 10% of gamma-ray sources are non-transient sources. These steady gamma-ray emitters include pulsars, neutron stars , and black hole candidates such as active galactic nuclei. In addition to electromagnetic radiation, a few other events originating from great distances may be observed from the Earth. In neutrino astronomy , astronomers use heavily shielded underground facilities such as SAGE , GALLEX , and Kamioka II/III for
630-453: A horizontal plane in order to ascertain the cardinal directions, the latitude of the point of observation, and the time of observation. This device finds mention in the works of Varāhamihira, Āryabhata, Bhāskara, Brahmagupta, among others. The Cross-staff , known as Yasti-yantra , was used by the time of Bhaskara II (1114–1185 CE). This device could vary from a simple stick to V-shaped staffs designed specifically for determining angles with
735-552: A model allows astronomers to select between several alternative or conflicting models. Theorists also modify existing models to take into account new observations. In some cases, a large amount of observational data that is inconsistent with a model may lead to abandoning it largely or completely, as for geocentric theory , the existence of luminiferous aether , and the steady-state model of cosmic evolution. Phenomena modeled by theoretical astronomers include: Modern theoretical astronomy reflects dramatic advances in observation since
840-410: A nocturnal polar rotation instrument consisted of a rectangular board with a slit and a set of pointers with concentric graduated circles. Time and other astronomical quantities could be calculated by adjusting the slit to the directions of α and β Ursa Minor . Ōhashi (2008) further explains that: "Its backside was made as a quadrant with a plumb and an index arm. Thirty parallel lines were drawn inside
945-671: A number of important astronomers. Richard of Wallingford (1292–1336) made major contributions to astronomy and horology , including the invention of the first astronomical clock, the Rectangulus which allowed for the measurement of angles between planets and other astronomical bodies, as well as an equatorium called the Albion which could be used for astronomical calculations such as lunar , solar and planetary longitudes and could predict eclipses . Nicole Oresme (1320–1382) and Jean Buridan (1300–1361) first discussed evidence for
1050-541: A number of observations were carried out". Following the arrival of the British East India Company in the 18th century, the Hindu and Islamic traditions were slowly displaced by European astronomy, though there were attempts at harmonising these traditions. The Indian scholar Mir Muhammad Hussain had travelled to England in 1774 to study Western science and, on his return to India in 1777, he wrote
1155-626: A personal observatory near Delhi , while Jahangir and Shah Jahan were also intending to build observatories but were unable to do so. After the decline of the Mughal Empire, it was a Hindu king, Jai Singh II of Amber , who attempted to revive both the Islamic and Hindu traditions of astronomy which were stagnating in his time. In the early 18th century, he built several large observatories called Yantra Mandirs in order to rival Ulugh Beg 's Samarkand observatory and in order to improve on
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#17327720192801260-578: A repeating cycle known as a saros . Following the Babylonians, significant advances in astronomy were made in ancient Greece and the Hellenistic world. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena. In the 3rd century BC, Aristarchus of Samos estimated the size and distance of the Moon and Sun , and he proposed a model of
1365-608: A substantial amount of work in the realms of theoretical and observational physics. Some areas of study for astrophysicists include their attempts to determine the properties of dark matter , dark energy , and black holes ; whether or not time travel is possible, wormholes can form, or the multiverse exists; and the origin and ultimate fate of the universe . Topics also studied by theoretical astrophysicists include Solar System formation and evolution ; stellar dynamics and evolution ; galaxy formation and evolution ; magnetohydrodynamics ; large-scale structure of matter in
1470-558: A wheel with 12 parts and 360 spokes (days), with a remainder of 5, making reference to the solar calendar. As in other traditions, there is a close association of astronomy and religion during the early history of the science, astronomical observation being necessitated by spatial and temporal requirements of correct performance of religious ritual. Thus, the Shulba Sutras , texts dedicated to altar construction, discusses advanced mathematics and basic astronomy. Vedanga Jyotisha
1575-427: Is visible light , or more generally electromagnetic radiation . Observational astronomy may be categorized according to the corresponding region of the electromagnetic spectrum on which the observations are made. Some parts of the spectrum can be observed from the Earth's surface, while other parts are only observable from either high altitudes or outside the Earth's atmosphere. Specific information on these subfields
1680-590: Is a branch of astronomy that studies the universe as a whole. Astronomy is one of the oldest natural sciences. The early civilizations in recorded history made methodical observations of the night sky . These include the Egyptians , Babylonians , Greeks , Indians , Chinese , Maya , and many ancient indigenous peoples of the Americas . In the past, astronomy included disciplines as diverse as astrometry , celestial navigation , observational astronomy , and
1785-893: Is a star's luminosity . As of June 2011, the catalog includes objects up to 25 Jupiter masses, an increase on the previous inclusion criteria of 20 Jupiter masses. As of 2016 this limit was increased to 60 Jupiter masses based on a study of mass–density relationships. Astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics , physics , and chemistry in order to explain their origin and their overall evolution . Objects of interest include planets , moons , stars , nebulae , galaxies , meteoroids , asteroids , and comets . Relevant phenomena include supernova explosions, gamma ray bursts , quasars , blazars , pulsars , and cosmic microwave background radiation . More generally, astronomy studies everything that originates beyond Earth's atmosphere . Cosmology
1890-584: Is absorbed by the Earth's atmosphere, requiring observations at these wavelengths to be performed from the upper atmosphere or from space. Ultraviolet astronomy is best suited to the study of thermal radiation and spectral emission lines from hot blue stars ( OB stars ) that are very bright in this wave band. This includes the blue stars in other galaxies, which have been the targets of several ultraviolet surveys. Other objects commonly observed in ultraviolet light include planetary nebulae , supernova remnants , and active galactic nuclei. However, as ultraviolet light
1995-595: Is also believed that the ruins at Great Zimbabwe and Timbuktu may have housed astronomical observatories. In Post-classical West Africa , Astronomers studied the movement of stars and relation to seasons, crafting charts of the heavens as well as precise diagrams of orbits of the other planets based on complex mathematical calculations. Songhai historian Mahmud Kati documented a meteor shower in August 1583. Europeans had previously believed that there had been no astronomical observation in sub-Saharan Africa during
2100-583: Is an inseparable part of the discipline of astrobiology. Astrobiology concerns itself with interpretation of existing scientific data , and although speculation is entertained to give context, astrobiology concerns itself primarily with hypotheses that fit firmly into existing scientific theories . This interdisciplinary field encompasses research on the origin of planetary systems , origins of organic compounds in space , rock-water-carbon interactions, abiogenesis on Earth, planetary habitability , research on biosignatures for life detection, and studies on
2205-592: Is another of the earliest known Indian texts on astronomy, it includes the details about the Sun, Moon, nakshatras , lunisolar calendar . The Vedanga Jyotisha describes rules for tracking the motions of the Sun and the Moon for the purposes of ritual. According to the Vedanga Jyotisha, in a yuga or "era", there are 5 solar years, 67 lunar sidereal cycles, 1,830 days, 1,835 sidereal days and 62 synodic months. Greek astronomical ideas began to enter India in
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#17327720192802310-427: Is easily absorbed by interstellar dust , an adjustment of ultraviolet measurements is necessary. X-ray astronomy uses X-ray wavelengths . Typically, X-ray radiation is produced by synchrotron emission (the result of electrons orbiting magnetic field lines), thermal emission from thin gases above 10 (10 million) kelvins , and thermal emission from thick gases above 10 Kelvin. Since X-rays are absorbed by
2415-414: Is founded on the detection and analysis of infrared radiation, wavelengths longer than red light and outside the range of our vision. The infrared spectrum is useful for studying objects that are too cold to radiate visible light, such as planets, circumstellar disks or nebulae whose light is blocked by dust. The longer wavelengths of infrared can penetrate clouds of dust that block visible light, allowing
2520-464: Is from these clouds that solar systems form. Studies in this field contribute to the understanding of the formation of the Solar System , Earth's origin and geology, abiogenesis , and the origin of climate and oceans. Astrobiology is an interdisciplinary scientific field concerned with the origins , early evolution , distribution, and future of life in the universe . Astrobiology considers
2625-416: Is given below. Radio astronomy uses radiation with wavelengths greater than approximately one millimeter, outside the visible range. Radio astronomy is different from most other forms of observational astronomy in that the observed radio waves can be treated as waves rather than as discrete photons . Hence, it is relatively easier to measure both the amplitude and phase of radio waves, whereas this
2730-679: Is in a flourishing state." Another Indian text, the Gargi-Samhita , also similarly compliments the Yavanas (Greeks) noting they, though barbarians, must be respected as seers for their introduction of astronomy in India. Indian astronomy reached China with the expansion of Buddhism during the Later Han (25–220 CE). Further translation of Indian works on astronomy was completed in China by
2835-645: Is not as easily done at shorter wavelengths. Although some radio waves are emitted directly by astronomical objects, a product of thermal emission , most of the radio emission that is observed is the result of synchrotron radiation , which is produced when electrons orbit magnetic fields . Additionally, a number of spectral lines produced by interstellar gas , notably the hydrogen spectral line at 21 cm, are observable at radio wavelengths. A wide variety of other objects are observable at radio wavelengths, including supernovae , interstellar gas, pulsars , and active galactic nuclei . Infrared astronomy
2940-472: Is not extant. The text today known as Surya Siddhanta dates to the Gupta period and was received by Aryabhata . The classical era of Indian astronomy begins in the late Gupta era, in the 5th to 6th centuries. The Pañcasiddhāntikā by Varāhamihira (505 CE) approximates the method for determination of the meridian direction from any three positions of the shadow using a gnomon . By the time of Aryabhata
3045-475: Is one of the few sciences in which amateurs play an active role . This is especially true for the discovery and observation of transient events . Amateur astronomers have helped with many important discoveries, such as finding new comets. Astronomy (from the Greek ἀστρονομία from ἄστρον astron , "star" and -νομία -nomia from νόμος nomos , "law" or "culture") means "law of the stars" (or "culture of
3150-479: Is the branch of astronomy that employs the principles of physics and chemistry "to ascertain the nature of the astronomical objects , rather than their positions or motions in space". Among the objects studied are the Sun , other stars , galaxies , extrasolar planets , the interstellar medium and the cosmic microwave background . Their emissions are examined across all parts of the electromagnetic spectrum , and
3255-453: Is the measurement of the positions of celestial objects. Historically, accurate knowledge of the positions of the Sun, Moon, planets and stars has been essential in celestial navigation (the use of celestial objects to guide navigation) and in the making of calendars . Careful measurement of the positions of the planets has led to a solid understanding of gravitational perturbations , and an ability to determine past and future positions of
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3360-484: The Compton Gamma Ray Observatory or by specialized telescopes called atmospheric Cherenkov telescopes . The Cherenkov telescopes do not detect the gamma rays directly but instead detect the flashes of visible light produced when gamma rays are absorbed by the Earth's atmosphere. Most gamma-ray emitting sources are actually gamma-ray bursts , objects which only produce gamma radiation for
3465-708: The Defence Research and Development Organisation and the Indian Space Research Organisation's (ISRO) civilian space programme and launch vehicle technology. Bhaba established the Tata Institute of Fundamental Research and Vikram Sarabhai established the Physical Research Laboratory . These organisations researched cosmic radiation and conducted studies of the upper atmosphere . In 1950,
3570-524: The Earth's atmosphere , all X-ray observations must be performed from high-altitude balloons , rockets , or X-ray astronomy satellites . Notable X-ray sources include X-ray binaries , pulsars , supernova remnants , elliptical galaxies , clusters of galaxies , and active galactic nuclei . Gamma ray astronomy observes astronomical objects at the shortest wavelengths of the electromagnetic spectrum. Gamma rays may be observed directly by satellites such as
3675-643: The Latin translations of the 12th century , Muhammad al-Fazari 's Great Sindhind (based on the Surya Siddhanta and the works of Brahmagupta ), was translated into Latin in 1126 and was influential at the time. Many Indian works on astronomy and astrology were translated into Middle Persian in Gundeshapur the Sasanian Empire and later translated from Middle Persian into Arabic. In
3780-544: The Mauryan Empire , and the later expansion of the Indo-Greeks into India suggest that transmission of Greek astronomical ideas to India occurred during this period. The Greek concept of a spherical Earth surrounded by the spheres of planets, further influenced the astronomers like Varahamihira and Brahmagupta . Several Greco-Roman astrological treatises are also known to have been exported to India during
3885-977: The Milky Way , as its own group of stars was only proven in the 20th century, along with the existence of "external" galaxies. The observed recession of those galaxies led to the discovery of the expansion of the Universe . In 1919, when the Hooker Telescope was completed, the prevailing view was that the universe consisted entirely of the Milky Way Galaxy. Using the Hooker Telescope, Edwin Hubble identified Cepheid variables in several spiral nebulae and in 1922–1923 proved conclusively that Andromeda Nebula and Triangulum among others, were entire galaxies outside our own, thus proving that
3990-794: The Muslim world by the early 9th century. In 964, the Andromeda Galaxy , the largest galaxy in the Local Group , was described by the Persian Muslim astronomer Abd al-Rahman al-Sufi in his Book of Fixed Stars . The SN 1006 supernova , the brightest apparent magnitude stellar event in recorded history, was observed by the Egyptian Arabic astronomer Ali ibn Ridwan and Chinese astronomers in 1006. Iranian scholar Al-Biruni observed that, contrary to Ptolemy ,
4095-561: The Renaissance , Nicolaus Copernicus proposed a heliocentric model of the solar system. His work was defended by Galileo Galilei and expanded upon by Johannes Kepler . Kepler was the first to devise a system that correctly described the details of the motion of the planets around the Sun. However, Kepler did not succeed in formulating a theory behind the laws he wrote down. It was Isaac Newton , with his invention of celestial dynamics and his law of gravitation , who finally explained
4200-561: The Solar System where the Earth and planets rotated around the Sun, now called the heliocentric model. In the 2nd century BC, Hipparchus discovered precession , calculated the size and distance of the Moon and invented the earliest known astronomical devices such as the astrolabe . Hipparchus also created a comprehensive catalog of 1020 stars, and most of the constellations of the northern hemisphere derive from Greek astronomy. The Antikythera mechanism ( c. 150 –80 BC)
4305-568: The Three Kingdoms era (220–265 CE). However, the most detailed incorporation of Indian astronomy occurred only during the Tang dynasty (618–907 CE) when a number of Chinese scholars—such as Yi Xing — were versed both in Indian and Chinese astronomy . A system of Indian astronomy was recorded in China as Jiuzhi-li (718 CE), the author of which was an Indian by the name of Qutan Xida —a translation of Devanagari Gotama Siddha—the director of
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4410-573: The calendars in India: The oldest system, in many respects the basis of the classical one, is known from texts of about 1000 BCE. It divides an approximate solar year of 360 days into 12 lunar months of 27 (according to the early Vedic text Taittirīya Saṃhitā 4.4.10.1–3) or 28 (according to the Atharvaveda , the fourth of the Vedas, 19.7.1.) days. The resulting discrepancy was resolved by
4515-427: The interstellar medium . The study of the abundance of elements and isotope ratios in Solar System objects, such as meteorites , is also called cosmochemistry , while the study of interstellar atoms and molecules and their interaction with radiation is sometimes called molecular astrophysics. The formation, atomic and chemical composition, evolution and fate of molecular gas clouds is of special interest, because it
4620-470: The 17th century, the Mughal Empire saw a synthesis between Islamic and Hindu astronomy, where Islamic observational instruments were combined with Hindu computational techniques. While there appears to have been little concern for planetary theory, Muslim and Hindu astronomers in India continued to make advances in observational astronomy and produced nearly a hundred Zij treatises. Humayun built
4725-442: The 1990s, including studies of the cosmic microwave background , distant supernovae and galaxy redshifts , which have led to the development of a standard model of cosmology . This model requires the universe to contain large amounts of dark matter and dark energy whose nature is currently not well understood, but the model gives detailed predictions that are in excellent agreement with many diverse observations. Astrophysics
4830-705: The 4th century BCE following the conquests of Alexander the Great . By the early centuries of the Common Era, Indo-Greek influence on the astronomical tradition is visible, with texts such as the Yavanajataka and Romaka Siddhanta . Later astronomers mention the existence of various siddhantas during this period, among them a text known as the Surya Siddhanta . These were not fixed texts but rather an oral tradition of knowledge, and their content
4935-628: The 6th century, the Romaka Siddhanta ("Doctrine of the Romans"), and the Paulisa Siddhanta ("Doctrine of Paul ") were considered as two of the five main astrological treatises, which were compiled by Varāhamihira in his Pañca-siddhāntikā ("Five Treatises"), a compendium of Greek, Egyptian, Roman and Indian astronomy. Varāhamihira goes on to state that "The Greeks, indeed, are foreigners, but with them this science (astronomy)
5040-403: The Earth's atmosphere and of their physical and chemical properties", while "astrophysics" refers to the branch of astronomy dealing with "the behavior, physical properties, and dynamic processes of celestial objects and phenomena". In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu , "astronomy" may be used to describe the qualitative study of
5145-701: The Kerala school (active 1380 to 1632) involved higher order polynomials and other cutting-edge algebra; many neatly were put to use, principally for predicting motions and alignments within the Solar System. During 1920, astronomers like Sisir Kumar Mitra , C.V. Raman and Meghnad Saha worked on various projects such as sounding of the ionosphere through ground-based radio and the Saha ionisation equation . Homi J. Bhaba and Vikram Sarabhai made significant contributions. A. P. J. Abdul Kalam also known as Missile Man of India assisted in development and research for
5250-404: The Sun inferred from the Moon's position at Full Moon, when the Sun is on the opposite side of the Moon. The position of the Sun at midnight was calculated from the nakṣatra that culminated on the meridian at that time, the Sun then being in opposition to that nakṣatra . Among the devices used for astronomy was gnomon , known as Sanku , in which the shadow of a vertical rod is applied on
5355-527: The Sun's apogee (highest point in the heavens) was mobile, not fixed. Some of the prominent Islamic (mostly Persian and Arab) astronomers who made significant contributions to the science include Al-Battani , Thebit , Abd al-Rahman al-Sufi , Biruni , Abū Ishāq Ibrāhīm al-Zarqālī , Al-Birjandi , and the astronomers of the Maragheh and Samarkand observatories. Astronomers during that time introduced many Arabic names now used for individual stars . It
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#17327720192805460-584: The Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the Universe, or the Ptolemaic system , named after Ptolemy . A particularly important early development was the beginning of mathematical and scientific astronomy, which began among the Babylonians , who laid the foundations for the later astronomical traditions that developed in many other civilizations. The Babylonians discovered that lunar eclipses recurred in
5565-516: The Tang dynasty's national astronomical observatory. Fragments of texts during this period indicate that Arabs adopted the sine function (inherited from Indian mathematics) instead of the chords of arc used in Hellenistic mathematics . Another Indian influence was an approximate formula used for timekeeping by Muslim astronomers . Through Islamic astronomy, Indian astronomy had an influence on European astronomy via Arabic translations. During
5670-535: The age of the Universe and size of the Observable Universe. Theoretical astronomy led to speculations on the existence of objects such as black holes and neutron stars , which have been used to explain such observed phenomena as quasars , pulsars , blazars , and radio galaxies . Physical cosmology made huge advances during the 20th century. In the early 1900s the model of the Big Bang theory
5775-426: The armillary sphere was composed between 1380 and 1460 CE by Parameśvara . On the subject of the usage of the armillary sphere in India, Ōhashi (2008) writes: "The Indian armillary sphere ( gola-yantra ) was based on equatorial coordinates, unlike the Greek armillary sphere, which was based on ecliptical coordinates, although the Indian armillary sphere also had an ecliptical hoop. Probably, the celestial coordinates of
5880-665: The astronomical tables compiled by Philippe de La Hire in 1702. After examining La Hire's work, Jai Singh concluded that the observational techniques and instruments used in European astronomy were inferior to those used in India at the time – it is uncertain whether he was aware of the Copernican Revolution via the Jesuits. He did, however, employ the use of telescopes . In his Zij-i Muhammad Shahi , he states: "telescopes were constructed in my kingdom and using them
5985-486: The atmosphere itself produces significant infrared emission. Consequently, infrared observatories have to be located in high, dry places on Earth or in space. Some molecules radiate strongly in the infrared. This allows the study of the chemistry of space; more specifically it can detect water in comets. Historically, optical astronomy, which has been also called visible light astronomy, is the oldest form of astronomy. Images of observations were originally drawn by hand. In
6090-595: The currently confirmed extrasolar planets as well as a database of unconfirmed planet detections. The databases are frequently updated with new data from peer-reviewed publications and conferences. In their respective pages, the planets are listed along with their basic properties, including the year of planet's discovery, mass , radius , orbital period , semi-major axis , eccentricity , inclination , longitude of periastron , time of periastron , maximum time variation , and time of transit , including all error range values. The individual planet data pages also contain
6195-481: The data on the parent star, including name, distance in parsecs , spectral type , effective temperature , apparent magnitude , mass , radius , age , and celestial coordinates ( Right Ascension and Declination ). Even when they are known, not all of these figures are listed in the interactive spreadsheet catalog, and many missing planet figures that would simply require the application of Kepler's third law of motion are left blank. Most notably absent on all pages
6300-408: The department is historically affiliated with a physics department, and many professional astronomers have physics rather than astronomy degrees. Some titles of the leading scientific journals in this field include The Astronomical Journal , The Astrophysical Journal , and Astronomy & Astrophysics . In early historic times, astronomy only consisted of the observation and predictions of
6405-474: The detection of neutrinos . The vast majority of the neutrinos streaming through the Earth originate from the Sun , but 24 neutrinos were also detected from supernova 1987A . Cosmic rays , which consist of very high energy particles (atomic nuclei) that can decay or be absorbed when they enter the Earth's atmosphere, result in a cascade of secondary particles which can be detected by current observatories. Some future neutrino detectors may also be sensitive to
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#17327720192806510-635: The earlier Hindu computations in the Siddhantas and Islamic observations in Zij-i-Sultani . The instruments he used were influenced by Islamic astronomy, while the computational techniques were derived from Hindu astronomy. Some scholars have suggested that knowledge of the results of the Kerala school of astronomy and mathematics may have been transmitted to Europe through the trade route from Kerala by traders and Jesuit missionaries. Kerala
6615-536: The earliest roots of Indian astronomy can be dated to the period of Indus Valley civilisation or earlier. Astronomy later developed as a discipline of Vedanga , or one of the "auxiliary disciplines" associated with the study of the Vedas dating 1500 BCE or older. The oldest known text is the Vedanga Jyotisha , dated to 1400–1200 BCE (with the extant form possibly from 700 to 600 BCE). Indian astronomy
6720-515: The eighteenth century. The observatory in Mathura is not extant, but those in Delhi, Jaipur , Ujjain , and Banaras are. There are several huge instruments based on Hindu and Islamic astronomy. For example, the samrāt.-yantra (emperor instrument) is a huge sundial which consists of a triangular gnomon wall and a pair of quadrants toward the east and west of the gnomon wall. Time has been graduated on
6825-575: The first few centuries of the present era. The Yavanajataka is a Sanskrit text of the 3rd century CE on Greek horoscopy and mathematical astronomy. Rudradaman 's capital at Ujjain "became the Greenwich of Indian astronomers and the Arin of the Arabic and Latin astronomical treatises; for it was he and his successors who encouraged the introduction of Greek horoscopy and astronomy into India." Later in
6930-669: The heliocentric system into the Zij tradition. Jantar (means yantra, machine); mantar (means calculate). Jai Singh II in the 18th century took great interest in science and astronomy. He made various Jantar Mantars in Jaipur , Delhi , Ujjain , Varanasi and Mathura . The Jaipur instance has 19 different astronomical calculators. These comprise live and forward-calculating astronomical clocks (calculators) for days, eclipses, visibility of key constellations which are not year-round northern polar ones thus principally but not exclusively those of
7035-450: The help of a calibrated scale. The clepsydra ( Ghatī-yantra ) was used in India for astronomical purposes until recent times. Ōhashi (2008) notes that: "Several astronomers also described water-driven instruments such as the model of fighting sheep." The armillary sphere was used for observation in India since early times, and finds mention in the works of Āryabhata (476 CE). The Goladīpikā —a detailed treatise dealing with globes and
7140-444: The intercalation of a leap month every 60 months. Time was reckoned by the position marked off in constellations on the ecliptic in which the Moon rises daily in the course of one lunation (the period from New Moon to New Moon) and the Sun rises monthly in the course of one year. These constellations ( nakṣatra ) each measure an arc of 13° 20 ′ of the ecliptic circle. The positions of the Moon were directly observable, and those of
7245-414: The introduction of new technology, including the spectroscope and photography . Joseph von Fraunhofer discovered about 600 bands in the spectrum of the Sun in 1814–15, which, in 1859, Gustav Kirchhoff ascribed to the presence of different elements. Stars were proven to be similar to the Earth's own Sun, but with a wide range of temperatures , masses , and sizes. The existence of the Earth's galaxy,
7350-499: The junction stars of the lunar mansions were determined by the armillary sphere since the seventh century or so. There was also a celestial globe rotated by flowing water." An instrument invented by the mathematician and astronomer Bhaskara II (1114–1185 CE) consisted of a rectangular board with a pin and an index arm. This device—called the Phalaka-yantra —was used to determine time from the Sun's altitude. The Kapālayantra
7455-579: The late 19th century and most of the 20th century, images were made using photographic equipment. Modern images are made using digital detectors, particularly using charge-coupled devices (CCDs) and recorded on modern medium. Although visible light itself extends from approximately 4000 Å to 7000 Å (400 nm to 700 nm), that same equipment can be used to observe some near-ultraviolet and near-infrared radiation. Ultraviolet astronomy employs ultraviolet wavelengths between approximately 100 and 3200 Å (10 to 320 nm). Light at those wavelengths
7560-576: The making of calendars . Professional astronomy is split into observational and theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects. This data is then analyzed using basic principles of physics. Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. These two fields complement each other. Theoretical astronomy seeks to explain observational results and observations are used to confirm theoretical results. Astronomy
7665-478: The medieval period and into the 16th or 17th century, especially within the Kerala school of astronomy and mathematics . Some of the earliest forms of astronomy can be dated to the period of Indus Valley civilisation , or earlier. Some cosmological concepts are present in the Vedas , as are notions of the movement of heavenly bodies and the course of the year. The Rig Veda is one of the oldest pieces of Indian literature. Rig Veda 1-64-11 & 48 describes time as
7770-412: The motion of planets was treated to be elliptical rather than circular. Other topics included definitions of different units of time, eccentric models of planetary motion, epicyclic models of planetary motion, and planetary longitude corrections for various terrestrial locations. The divisions of the year were on the basis of religious rites and seasons ( Ṛtú ). The duration from mid March—mid May
7875-593: The motions of objects visible to the naked eye. In some locations, early cultures assembled massive artifacts that may have had some astronomical purpose. In addition to their ceremonial uses, these observatories could be employed to determine the seasons, an important factor in knowing when to plant crops and in understanding the length of the year. As civilizations developed, most notably in Egypt , Mesopotamia , Greece , Persia , India , China , and Central America , astronomical observatories were assembled and ideas on
7980-417: The motions of the planets. Newton also developed the reflecting telescope . Improvements in the size and quality of the telescope led to further discoveries. The English astronomer John Flamsteed catalogued over 3000 stars. More extensive star catalogues were produced by Nicolas Louis de Lacaille . The astronomer William Herschel made a detailed catalog of nebulosity and clusters, and in 1781 discovered
8085-406: The nature of the Universe began to develop. Most early astronomy consisted of mapping the positions of the stars and planets, a science now referred to as astrometry . From these observations, early ideas about the motions of the planets were formed, and the nature of the Sun, Moon and the Earth in the Universe were explored philosophically. The Earth was believed to be the center of the Universe with
8190-494: The observation of young stars embedded in molecular clouds and the cores of galaxies. Observations from the Wide-field Infrared Survey Explorer (WISE) have been particularly effective at unveiling numerous galactic protostars and their host star clusters . With the exception of infrared wavelengths close to visible light, such radiation is heavily absorbed by the atmosphere, or masked, as
8295-431: The only examples of seamless metal globes. These Mughal metallurgists developed the method of lost-wax casting in order to produce these globes. According to David Pingree , there are a number of Indian astronomical texts dated to the sixth century CE or later with a high degree of certainty. There is substantial similarity between these and pre-Ptolemaic Greek astronomy. Pingree believes that these similarities suggest
8400-553: The particles produced when cosmic rays hit the Earth's atmosphere. Gravitational-wave astronomy is an emerging field of astronomy that employs gravitational-wave detectors to collect observational data about distant massive objects. A few observatories have been constructed, such as the Laser Interferometer Gravitational Observatory LIGO . LIGO made its first detection on 14 September 2015, observing gravitational waves from
8505-497: The planet Uranus , the first new planet found. During the 18–19th centuries, the study of the three-body problem by Leonhard Euler , Alexis Claude Clairaut , and Jean le Rond d'Alembert led to more accurate predictions about the motions of the Moon and planets. This work was further refined by Joseph-Louis Lagrange and Pierre Simon Laplace , allowing the masses of the planets and moons to be estimated from their perturbations. Significant advances in astronomy came about with
8610-470: The planets with great accuracy, a field known as celestial mechanics . More recently the tracking of near-Earth objects will allow for predictions of close encounters or potential collisions of the Earth with those objects. The measurement of stellar parallax of nearby stars provides a fundamental baseline in the cosmic distance ladder that is used to measure the scale of the Universe. Parallax measurements of nearby stars provide an absolute baseline for
8715-514: The potential for life to adapt to challenges on Earth and in outer space . Cosmology (from the Greek κόσμος ( kosmos ) "world, universe" and λόγος ( logos ) "word, study" or literally "logic") could be considered the study of the Universe as a whole. Indian astronomy Indian astronomy refers to astronomy practiced in the Indian subcontinent . It has a long history stretching from pre-historic to modern times . Some of
8820-596: The pre-colonial Middle Ages, but modern discoveries show otherwise. For over six centuries (from the recovery of ancient learning during the late Middle Ages into the Enlightenment), the Roman Catholic Church gave more financial and social support to the study of astronomy than probably all other institutions. Among the Church's motives was finding the date for Easter . Medieval Europe housed
8925-458: The properties examined include luminosity , density , temperature , and chemical composition. Because astrophysics is a very broad subject, astrophysicists typically apply many disciplines of physics, including mechanics , electromagnetism , statistical mechanics , thermodynamics , quantum mechanics , relativity , nuclear and particle physics , and atomic and molecular physics . In practice, modern astronomical research often involves
9030-473: The properties of more distant stars, as their properties can be compared. Measurements of the radial velocity and proper motion of stars allow astronomers to plot the movement of these systems through the Milky Way galaxy. Astrometric results are the basis used to calculate the distribution of speculated dark matter in the galaxy. During the 1990s, the measurement of the stellar wobble of nearby stars
9135-409: The quadrant, and trigonometrical calculations were done graphically. After determining the sun's altitude with the help of the plumb, time was calculated graphically with the help of the index arm." Ōhashi (2008) reports on the observatories constructed by Jai Singh II of Amber : The Mahārāja of Jaipur, Sawai Jai Singh (1688–1743 CE), constructed five astronomical observatories at the beginning of
9240-510: The quadrants. The seamless celestial globe invented in Mughal India , specifically Lahore and Kashmir , is considered to be one of the most impressive astronomical instruments and remarkable feats in metallurgy and engineering. All globes before and after this were seamed, and in the 20th century, it was believed by metallurgists to be technically impossible to create a metal globe without any seams , even with modern technology. It
9345-459: The question of whether extraterrestrial life exists, and how humans can detect it if it does. The term exobiology is similar. Astrobiology makes use of molecular biology , biophysics , biochemistry , chemistry , astronomy, physical cosmology , exoplanetology and geology to investigate the possibility of life on other worlds and help recognize biospheres that might be different from that on Earth. The origin and early evolution of life
9450-547: The rise of Greek culture in the east , Hellenistic astronomy filtered eastwards to India, where it profoundly influenced the local astronomical tradition. For example, Hellenistic astronomy is known to have been practised near India in the Greco-Bactrian city of Ai-Khanoum from the 3rd century BCE. Various sun-dials, including an equatorial sundial adjusted to the latitude of Ujjain have been found in archaeological excavations there. Numerous interactions with
9555-425: The rotation of the Earth, furthermore, Buridan also developed the theory of impetus (predecessor of the modern scientific theory of inertia ) which was able to show planets were capable of motion without the intervention of angels. Georg von Peuerbach (1423–1461) and Regiomontanus (1436–1476) helped make astronomical progress instrumental to Copernicus's development of the heliocentric model decades later. During
9660-436: The stars" depending on the translation). Astronomy should not be confused with astrology , the belief system which claims that human affairs are correlated with the positions of celestial objects. Although the two fields share a common origin, they are now entirely distinct. "Astronomy" and " astrophysics " are synonyms. Based on strict dictionary definitions, "astronomy" refers to "the study of objects and matter outside
9765-477: The subject, whereas "astrophysics" is used to describe the physics-oriented version of the subject. However, since most modern astronomical research deals with subjects related to physics, modern astronomy could actually be called astrophysics. Some fields, such as astrometry , are purely astronomy rather than also astrophysics. Various departments in which scientists carry out research on this subject may use "astronomy" and "astrophysics", partly depending on whether
9870-551: The time. The Aryabhatiya is composed of four sections, covering topics such as units of time, methods for determining the positions of planets, the cause of day and night, and several other cosmological concepts. Later, Indian astronomy significantly influenced Muslim astronomy , Chinese astronomy , European astronomy and others. Other astronomers of the classical era who further elaborated on Aryabhata's work include Brahmagupta , Varahamihira and Lalla . An identifiable native Indian astronomical tradition remained active throughout
9975-548: The universe consists of a multitude of galaxies. With this Hubble formulated the Hubble constant , which allowed for the first time a calculation of the age of the Universe and size of the Observable Universe, which became increasingly precise with better meassurements, starting at 2 billion years and 280 million light-years, until 2006 when data of the Hubble Space Telescope allowed a very accurate calculation of
10080-409: The universe; origin of cosmic rays ; general relativity and physical cosmology , including string cosmology and astroparticle physics . Astrochemistry is the study of the abundance and reactions of molecules in the Universe , and their interaction with radiation . The discipline is an overlap of astronomy and chemistry . The word "astrochemistry" may be applied to both the Solar System and
10185-411: The zodiac. Astronomers abroad were invited and admired complexity of certain devices. As brass time-calculators are imperfect, and to help in their precise re-setting so as to match true locally experienced time, there remains equally his Samrat Yantra, the largest sundial in the world. It divides each daylit hour as to solar 15-minute, 1-minute and 6-second subunits. Other notable include: Models of
10290-640: Was used to detect large extrasolar planets orbiting those stars. Theoretical astronomers use several tools including analytical models and computational numerical simulations ; each has its particular advantages. Analytical models of a process are better for giving broader insight into the heart of what is going on. Numerical models reveal the existence of phenomena and effects otherwise unobserved. Theorists in astronomy endeavor to create theoretical models that are based on existing observations and known physics, and to predict observational consequences of those models. The observation of phenomena predicted by
10395-475: Was an equatorial sundial instrument used to determine the Sun's azimuth . Kartarī-yantra combined two semicircular board instruments to give rise to a 'scissors instrument'. Introduced from the Islamic world and first finding mention in the works of Mahendra Sūri —the court astronomer of Firuz Shah Tughluq (1309–1388 CE)—the astrolabe was further mentioned by Padmanābha (1423 CE) and Rāmacandra (1428 CE) as its use grew in India. Invented by Padmanābha ,
10500-465: Was an early analog computer designed to calculate the location of the Sun , Moon , and planets for a given date. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe. Astronomy flourished in the Islamic world and other parts of the world. This led to the emergence of the first astronomical observatories in
10605-536: Was formulated, heavily evidenced by cosmic microwave background radiation , Hubble's law , and the cosmological abundances of elements . Space telescopes have enabled measurements in parts of the electromagnetic spectrum normally blocked or blurred by the atmosphere. In February 2016, it was revealed that the LIGO project had detected evidence of gravitational waves in the previous September. The main source of information about celestial bodies and other objects
10710-467: Was in continuous contact with China, Arabia and Europe. The existence of circumstantial evidence such as communication routes and a suitable chronology certainly make such a transmission a possibility. However, there is no direct evidence by way of relevant manuscripts that such a transmission took place. In the early 18th century, Jai Singh II of Amber invited European Jesuit astronomers to one of his Yantra Mandir observatories, who had bought back
10815-627: Was in the 1980s, however, that Emilie Savage-Smith discovered several celestial globes without any seams in Lahore and Kashmir. The earliest was invented in Kashmir by Ali Kashmiri ibn Luqman in 1589–90 CE during Akbar the Great 's reign; another was produced in 1659–60 CE by Muhammad Salih Tahtawi with Arabic and Sanskrit inscriptions; and the last was produced in Lahore by a Hindu metallurgist Lala Balhumal Lahuri in 1842 during Jagatjit Singh Bahadur 's reign. 21 such globes were produced, and these remain
10920-415: Was influenced by Greek astronomy beginning in the 4th century BCE and through the early centuries of the Common Era, for example by the Yavanajataka and the Romaka Siddhanta , a Sanskrit translation of a Greek text disseminated from the 2nd century. Indian astronomy flowered in the 5th–6th century, with Aryabhata , whose work, Aryabhatiya , represented the pinnacle of astronomical knowledge at
11025-475: Was taken to be spring ( vasanta ), mid May—mid July: summer ( grishma ), mid July—mid September: rains ( varsha ), mid September—mid November: autumn ( sharada ), mid November—mid January: winter ( hemanta ), mid January—mid March: the dews ( shishira ). In the Vedānga Jyotiṣa , the year begins with the winter solstice. Hindu calendars have several eras : J.A.B. van Buitenen (2008) reports on
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