The ecliptic is the mean plane of the apparent path in the Earth's sky that the Sun follows over the course of one year. This plane of reference is coplanar with Earth's orbit around the Sun; the ecliptic is not noticeable from Earth's surface because the planet's rotation carries the observer through the daily cycles of sunrise and sunset, which obscure the Sun's apparent motion against the background of stars during the year. The motions as described above are simplifications. Due to the movement of Earth around the Earth–Moon center of mass, the apparent path of the Sun wobbles with a period of about one month. Due to further perturbations by the other planets of the Solar System, the Earth–Moon barycenter wobbles around a mean position in a complex fashion; the ecliptic is the apparent path of the Sun throughout the course of a year. Because Earth takes one year to orbit the Sun, the apparent position of the Sun takes one year to make a complete circuit of the ecliptic. With more than 365 days in one year, the Sun moves a little less than 1° eastward every day.
This small difference in the Sun's position against the stars causes any particular spot on Earth's surface to catch up with the Sun about four minutes each day than it would if Earth would not orbit. Again, this is a simplification, based on a hypothetical Earth that orbits at uniform speed around the Sun; the actual speed with which Earth orbits the Sun varies during the year, so the speed with which the Sun seems to move along the ecliptic varies. For example, the Sun is north of the celestial equator for about 185 days of each year, south of it for about 180 days; the variation of orbital speed accounts for part of the equation of time. Because Earth's rotational axis is not perpendicular to its orbital plane, Earth's equatorial plane is not coplanar with the ecliptic plane, but is inclined to it by an angle of about 23.4°, known as the obliquity of the ecliptic. If the equator is projected outward to the celestial sphere, forming the celestial equator, it crosses the ecliptic at two points known as the equinoxes.
The Sun, in its apparent motion along the ecliptic, crosses the celestial equator at these points, one from south to north, the other from north to south. The crossing from south to north is known as the vernal equinox known as the first point of Aries and the ascending node of the ecliptic on the celestial equator; the crossing from north to south is descending node. The orientation of Earth's axis and equator are not fixed in space, but rotate about the poles of the ecliptic with a period of about 26,000 years, a process known as lunisolar precession, as it is due to the gravitational effect of the Moon and Sun on Earth's equatorial bulge; the ecliptic itself is not fixed. The gravitational perturbations of the other bodies of the Solar System cause a much smaller motion of the plane of Earth's orbit, hence of the ecliptic, known as planetary precession; the combined action of these two motions is called general precession, changes the position of the equinoxes by about 50 arc seconds per year.
Once again, this is a simplification. Periodic motions of the Moon and apparent periodic motions of the Sun cause short-term small-amplitude periodic oscillations of Earth's axis, hence the celestial equator, known as nutation; this adds a periodic component to the position of the equinoxes. Obliquity of the ecliptic is the term used by astronomers for the inclination of Earth's equator with respect to the ecliptic, or of Earth's rotation axis to a perpendicular to the ecliptic, it is about 23.4° and is decreasing 0.013 degrees per hundred years due to planetary perturbations. The angular value of the obliquity is found by observation of the motions of Earth and other planets over many years. Astronomers produce new fundamental ephemerides as the accuracy of observation improves and as the understanding of the dynamics increases, from these ephemerides various astronomical values, including the obliquity, are derived; until 1983 the obliquity for any date was calculated from work of Newcomb, who analyzed positions of the planets until about 1895: ε = 23° 27′ 08″.26 − 46″.845 T − 0″.0059 T2 + 0″.00181 T3 where ε is the obliquity and T is tropical centuries from B1900.0 to the date in question.
From 1984, the Jet Propulsion Laboratory's DE series of computer-generated ephemerides took over as the fundamental ephemeris of the Astronomical Almanac. Obliquity based on DE200, which analyzed observations from 1911 to 1979, was calculated: ε = 23° 26′ 21″.45 − 46″.815 T − 0″.0006 T2 + 0″.00181 T3 where hereafter T is Julian centuries from J2000.0. JPL's fundamental ephemerides have been continually updated; the Astronomical Almanac for 2010 specifies:ε = 23° 26′ 21″.406 − 46″.836769 T − 0″.0001831 T2 + 0″.00200340 T3 − 0″.576×10−6 T4 − 4″.34×10−8 T5 These expressions for the obliquity are intended for high precision over a short time span ± several centuries. J. Laskar computed an expression to order T10 good to 0″.04/1000 years over 10,000 years. All of these expressions are for the mean obliquity, that is, without the nutation of the equator included; the true or instantaneous obliquity includes the nutation. Most of the major bodies of the Solar System o
Proper motion is the astronomical measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more distant stars. The components for proper motion in the equatorial coordinate system are given in the direction of right ascension and of declination, their combined value is computed as the total proper motion. It has dimensions of angle per time arcseconds per year or milliarcseconds per year. Knowledge of the proper motion and radial velocity allows calculations of true stellar motion or velocity in space in respect to the Sun, by coordinate transformation, the motion in respect to the Milky Way. Proper motion is not "proper", because it includes a component due to the motion of the Solar System itself. Over the course of centuries, stars appear to maintain nearly fixed positions with respect to each other, so that they form the same constellations over historical time.
Ursa Major or Crux, for example, looks nearly the same now. However, precise long-term observations show that the constellations change shape, albeit slowly, that each star has an independent motion; this motion is caused by the movement of the stars relative to the Solar System. The Sun travels in a nearly circular orbit about the center of the Milky Way at a speed of about 220 km/s at a radius of 8 kPc from the center, which can be taken as the rate of rotation of the Milky Way itself at this radius; the proper motion is a two-dimensional vector and is thus defined by two quantities: its position angle and its magnitude. The first quantity indicates the direction of the proper motion on the celestial sphere, the second quantity is the motion's magnitude expressed in arcseconds per year or milliarcsecond per year. Proper motion may alternatively be defined by the angular changes per year in the star's right ascension and declination, using a constant epoch in defining these; the components of proper motion by convention are arrived at.
Suppose an object moves from coordinates to coordinates in a time Δt. The proper motions are given by: μ α = α 2 − α 1 Δ t, μ δ = δ 2 − δ 1 Δ t; the magnitude of the proper motion μ is given by the Pythagorean theorem: μ 2 = μ δ 2 + μ α 2 ⋅ cos 2 δ, μ 2 = μ δ 2 + μ α ∗ 2, where δ is the declination. The factor in cos2δ accounts for the fact that the radius from the axis of the sphere to its surface varies as cosδ, for example, zero at the pole. Thus, the component of velocity parallel to the equator corresponding to a given angular change in α is smaller the further north the object's location; the change μα, which must be multiplied by cosδ to become a component of the proper motion, is sometimes called the "proper motion in right ascension", μδ the "proper motion in declination". If the proper motion in right ascension has been converted by cosδ, the result is designated μα*. For example, the proper motion results in right ascension in the Hipparcos Catalogue have been converted. Hence, the individual proper motions in right ascension and declination are made equivalent for straightforward calculations of various other stellar motions.
The position angle θ is related to these components by: μ sin θ = μ α cos δ = μ α ∗, μ cos θ = μ δ. Motions in equatorial coordinates can be converted to motions in galactic coordinates. For the majority of stars seen in the sky, the observed proper motions are small and unremarkable; such stars are either faint or are distant, have changes of below 10 milliarcseconds per year, do not appear to move appreciably over many millennia. A few do have significant motions, are called high-proper motion stars. Motions can be in seemingly random directions. Two or more stars, double stars or open star clusters, which are moving in similar directions, exhibit so-called shared or common proper motion, suggesting they may be gravitationally attached or share similar motion in space. Barnard's Star has the largest proper motion of all stars, moving at 10.3 seconds of arc per year. L
Sidereal and tropical astrology
Sidereal and tropical are astrological terms used to describe two different definitions of a year. They are used as terms for two systems of ecliptic coordinates used in astrology. Both divide the ecliptic into a number of "signs" named after constellations, but while the sidereal system defines the signs based on the fixed stars, the tropical system defines it based on the position of vernal equinox in the northern hemisphere; because of the precession of the equinoxes, the two systems do not remain fixed relative to each other but drift apart by about 1.4 arc degrees per century. The tropical system was adopted during the Hellenistic period and remains prevalent in Western astrology. A sidereal system is used in Hindu astrology, in some 20th century systems of Western astrology. While classical tropical astrology is based on the orientation of the Earth relative to the Sun and planets of the solar system, sidereal astrology deals with the position of the Earth relative to both of these as well as the stars of the celestial sphere.
The actual positions of certain fixed stars as well as their constellations is an additional consideration in the horoscope. The classical zodiac was introduced in the neo-Babylonian period. At the time, the precession of the equinoxes had not been discovered. Classical Hellenistic astrology developed without consideration of the effects of precession; the discovery of the precession of the equinoxes is attributed to Hipparchus, a Greek astronomer active in the Hellenistic period. Ptolemy, writing some 250 years after Hipparchus, was thus aware of the effects of precession, he opted for a definition of the zodiac based on the point of the vernal equinox, i.e. the tropical system. While Ptolemy noted that Ophiuchus is in contact with the ecliptic, he was aware that the 12 signs were just conventional names for 30-degree segments; the Hindu Jyotisha system opted for defining the zodiac based on the fixed stars, i.e. directly tied to the eponymous zodiacal constellations, unlike Western astrological systems.
Traditional Hindu astrology is based on the sidereal or visible zodiac, accounting for the shift of the equinoxes by a correction called ayanamsa. The difference between the Vedic and the Western zodiacs is around 24 degrees; this corresponds to a separation of about 1,700 years, when the vernal equinox was at the center of the constellation Aries, the tropical and sidereal zodiacs coincided. The separation is believed to have taken place in the centuries following Ptolemy going back to Indo-Greek transmission of the system, but earlier Greek astronomers like Eudoxus spoke of a vernal equinox at 15° in Aries, while Greeks spoke of a vernal equinox at 8° and 0° in Aries, which suggests the use of a sidereal zodiac in Greece before Ptolemy and Hipparchus. Some western astrologists have shown interest in the sidereal system during the 20th century. Cyril Fagan assumed the origin of the zodiac to be based on a major conjunction that occurred in 786 BC, when the vernal equinox lay somewhere in mid-Aries corresponding to a difference of some 39 degrees or days.
Most sidereal astrologers divide the ecliptic into 12 equal signs of 30 degrees but aligned to the 12 zodiac constellations. Assuming an origin of the system in 786 BC, this results in a system identical to that of the classical tropical zodiac, shifted by 25.5 days, i.e. if in tropical astrology Aries is taken to begin at March 21, sidereal Aries will begin on April 15. A small number of sidereal astrologers do not take the astrological signs as an equal division of the ecliptic, but define their signs based on the actual width of the individual constellations, they include constellations that are disregarded by the traditional zodiac, but are still in contact with the ecliptic. Stephen Schmidt in 1970 introduced Astrology 14, a system with additional signs based on the constellations of Ophiuchus and Cetus. In 1995, Walter Berg introduced his 13-sign zodiac. Berg's system was well received in Japan after his book was translated by radio host Mizui Kumi in 1996. For the purpose of determining the constellations in contact with the ecliptic, the constellation boundaries as defined by the International Astronomical Union in 1930 are used.
For example, the Sun enters the IAU boundary of Aries on April 19 at the lower right corner, a position, still rather closer to the "body" of Pisces than of Aries. The IAU defined the constellation boundaries without consideration of astrological purposes; the dates the Sun passes through the 13 astronomical constellations of the ecliptic are listed below, accurate to the year 2011. The dates will progress by an increment of one day every 70.5 years. The corresponding tropical and sidereal dates are given as well. Great year Astrology and science Synoptical astrology "The Real Constellations of the Zodiac." Dr. Lee T. Shapiro, Vol 6, #1, Spring. "The Real, Real Constellations of the Zodiac." John Mosley, Vol. 28, # 4, December. "The Primer of Sidereal Astrology," Cyril Fagin and Brigadier R. C. Firebrace, American Federation of Astrologers, Inc. ISBN 0-86690-427-1 A History of Western Astrology, by S. Jim Tester, 1987, republished by Boydell Press,ISBN 0-85115-255-4, ISBN 978-0-85115-255-4 Raymond, Andrew.
Secrets of the Sphinx Mysteries of the Ages Revealed. Hawaii: U N I Productions. ISBN 0-9646954-6-4. Vedic astrology -- critically examined by Dieter Koch, with an extended discussion
Claudius Ptolemy was a Greco-Roman mathematician, astronomer and astrologer. He lived in the city of Alexandria in the Roman province of Egypt, wrote in Koine Greek, held Roman citizenship; the 14th-century astronomer Theodore Meliteniotes gave his birthplace as the prominent Greek city Ptolemais Hermiou in the Thebaid. This attestation is quite late, and, according to Gerald Toomer, the translator of his Almagest into English, there is no reason to suppose he lived anywhere other than Alexandria, he died there around AD 168. Ptolemy wrote several scientific treatises, three of which were of importance to Byzantine and Western European science; the first is the astronomical treatise now known as the Almagest, although it was entitled the Mathematical Treatise and known as the Great Treatise. The second is the Geography, a thorough discussion of the geographic knowledge of the Greco-Roman world; the third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day.
This is sometimes known as the Apotelesmatika but more known as the Tetrabiblos from the Greek meaning "Four Books" or by the Latin Quadripartitum. Ptolemaeus is a Greek name, it occurs once in Greek mythology, is of Homeric form. It was common among the Macedonian upper class at the time of Alexander the Great, there were several of this name among Alexander's army, one of whom made himself pharaoh in 323 BC: Ptolemy I Soter, the first king of the Ptolemaic Kingdom. All male kings of Hellenistic Egypt, until Egypt became a Roman province in 30 BC ending the Macedonian family's rule, were Ptolemies; the name Claudius is a Roman nomen. It would have suited custom if the first of Ptolemy's family to become a citizen took the nomen from a Roman called Claudius, responsible for granting citizenship. If, as was common, this was the emperor, citizenship would have been granted between AD 41 and 68; the astronomer would have had a praenomen, which remains unknown. The ninth-century Persian astronomer Abu Maʿshar presents Ptolemy as a member of Egypt's royal lineage, stating that the descendants of Alexander's general Ptolemy I, who ruled Egypt, were wise "and included Ptolemy the Wise, who composed the book of the Almagest".
Abu Maʿshar recorded a belief that a different member of this royal line "composed the book on astrology and attributed it to Ptolemy". We can evidence historical confusion on this point from Abu Maʿshar's subsequent remark "It is sometimes said that the learned man who wrote the book of astrology wrote the book of the Almagest; the correct answer is not known." There is little evidence on the subject of Ptolemy's ancestry, apart from what can be drawn from the details of his name. Ptolemy can be shown to have utilized Babylonian astronomical data, he was a Roman citizen, but was ethnically either a Greek or a Hellenized Egyptian. He was known in Arabic sources as "the Upper Egyptian", suggesting he may have had origins in southern Egypt. Arabic astronomers and physicists referred to him by his name in Arabic: بَطْلُمْيوس Baṭlumyus. Ptolemy's Almagest is the only surviving comprehensive ancient treatise on astronomy. Babylonian astronomers had developed arithmetical techniques for calculating astronomical phenomena.
Ptolemy, claimed to have derived his geometrical models from selected astronomical observations by his predecessors spanning more than 800 years, though astronomers have for centuries suspected that his models' parameters were adopted independently of observations. Ptolemy presented his astronomical models in convenient tables, which could be used to compute the future or past position of the planets; the Almagest contains a star catalogue, a version of a catalogue created by Hipparchus. Its list of forty-eight constellations is ancestral to the modern system of constellations, but unlike the modern system they did not cover the whole sky. Across Europe, the Middle East and North Africa in the Medieval period, it was the authoritative text on astronomy, with its author becoming an mythical figure, called Ptolemy, King of Alexandria; the Almagest was preserved, in Arabic manuscripts. Because of its reputation, it was sought and was translated twice into Latin in the 12th century, once in Sicily and again in Spain.
Ptolemy's model, like those of his predecessors, was geocentric and was universally accepted until the appearance of simpler heliocentric models during the scientific revolution. His Planetary Hypotheses went beyond the mathematical model of the Almagest to present a physical realization of the universe as a set of nested spheres, in which he used the epicycles of his planetary model to compute the dimensions of the universe, he estimated the Sun was at an average dis
Indian astronomy has a long history stretching from pre-historic to modern times. Some of the earliest roots of Indian astronomy can be dated to the period of Indus Valley Civilization or earlier. Astronomy 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. Greek astronomy was influenced by Indian astronomy and vice versa 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 Aryabhatiya represented the pinnacle of astronomical knowledge at the time; the Indian astronomy influenced Muslim astronomy, Chinese astronomy, European astronomy, others. Other astronomers of the classical era who further elaborated on Aryabhata's work include Brahmagupta and Lalla.
An identifiable native Indian astronomical tradition remained active throughout the medieval period and into the 16th or 17th century within the Kerala school of astronomy and mathematics. Some of the earliest forms of astronomy can be dated to the period of Indus Valley Civilization, 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. 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 is another of the earliest known Indian texts on astronomy, it includes the details about the Sun, nakshatras, lunisolar calendar. Greek astronomical ideas began to enter India in 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. 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, their content is not extant. The text today known as Surya Siddhanta was received by Aryabhata; the classical era of Indian astronomy begins in the 5th to 6th centuries. The Pañcasiddhāntikā by Varāhamihira approximates the method for determination of the meridian direction from any three positions of the shadow using a gnomon. By the time of Aryabhata 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, planetary longitude corrections for various terrestrial locations; the divisions of the year were on the basis of religious seasons.
The duration from mid March—Mid May was taken to be spring, mid May—mid July: summer, mid July—mid September: rains, mid September—mid November: autumn, mid November—mid January: winter, mid January—mid March: dew. In the Vedānga Jyotiṣa, the year begins with the winter solstice. Hindu calendars have several eras: The Hindu calendar, counting from the start of the Kali Yuga, has its epoch on 18 February 3102 BCE Julian; the Vikrama Samvat calendar, introduced about the 12th century, counts from 56–57 BCE. The "Saka Era", used in some Hindu calendars and in the Indian national calendar, has its epoch near the vernal equinox of year 78; the Saptarshi calendar traditionally has its epoch at 3076 BCE. J. A. B. Van Buitenen reports on 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 28 days. The resulting discrepancy was resolved by 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 and the Sun rises monthly in the course of one year. These constellations each measure an arc of 13° 20′ of the ecliptic circle; the positions of the Moon were directly observable, those of 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 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 a horizontal plane in order to ascertain the cardinal directions, the latitude of the point of observation, the time of observation; this device finds mention in the works of Varāhamihira, Āryabhata, Bhāskara, among others. The Cross-staff, known as Yasti-yantra, was used by the time of Bhaskara II.
This device could vary from a simple stick to V-shaped staffs designed for determining angles with the help of a calibrated scale. The clepsydra was used in India for astronomical purposes until recent times. Ōhashi notes that: "Se
The Surya Siddhanta is the name of a Sanskrit treatise in Indian astronomy from the late 4th-century or early 5th-century CE. The text survives in several versions, was cited and extensively quoted in a 6th-century CE text by Varahamihira, was revised for several centuries under the same title, it has fourteen chapters. A 12th-century manuscript of the text was translated into English by Burgess in 1860; the Surya Siddhanta describes rules to calculate the motions of various planets and the moon relative to various constellations, diameters of various planets, calculates the orbits of various astronomical bodies. The text asserts, according to Srivatsava, that the earth is of a spherical shape, it treats earth as stationary globe around which sun orbits, makes no mention of Uranus, Neptune or Pluto. It calculates the earth's diameter to be 8,000 miles, diameter of moon as 2,400 miles and the distance between moon and earth to be 258,000 miles; the text is known for some of earliest known discussion of sexagesimal fractions and trigonometric functions.
The Surya Siddhanta is one of the several astronomy-related Hindu texts, influenced by ancient pre-Ptolemy Greek ideas. It represents a functional system; the text was influential on the solar year computations of the luni-solar Hindu calendar. In a work called the Pañca-siddhāntikā composed in the sixth century by Varāhamihira, five astronomical treatises are named and summarised: Paulīśa-siddhānta, Romaka-siddhānta, Vasiṣṭha-siddhānta, Sūrya-siddhānta, Paitāmaha-siddhānta; the surviving version of the text is dated to about the 6th-century BC by Srivastava. Most scholars, place the text variously from the 4th-century to 5th-century CE. According to John Bowman, the earliest version of the text existed between 350-400 CE wherein it referenced sexagesimal fractions and trigonometric functions, but the text was a living document and revised through about the 10th-century. One of the evidence for the Surya Siddhanta being a living text is the work of medieval Indian scholar Utpala, who cites and quotes ten verses from a version of Surya Siddhanta, but these ten verses are not found in any surviving manuscripts of the text.
According to Kim Plofker, large portions of the more ancient Sūrya-siddhānta was incorporated into the Panca siddhantika text, a new version of the Surya Siddhanta was revised and composed around 800 CE. Some scholars refer to Panca siddhantika as the old Surya Siddhanta and date it to 505 CE; the Surya Siddhanta is a text on astronomy and time keeping, an idea that appears much earlier as the field of Jyotisha of the Vedic period. The field of Jyotisha deals with ascertaining time forecasting auspicious day and time for Vedic rituals. Max Muller, quoting passages by Garga and others for Vedic sacrifices, states that the ancient Vedic texts describe four measures of time – savana, solar and sidereal, as well as twenty seven constellations using Taras; the idea of twenty eight constellations and movement of astronomical bodies appears, states David Pingree – a professor of History of Mathematics and Classics, in the Hindu text Atharvaveda. Scholars have speculated. However, states Pingree, this hypothesis has not been proven because no cuneiform tablet or evidence from Mesopotamian antiquity has yet been deciphered that presents this theory or calculations.
According to Pingree, the influence may have flowed the other way then flowed into India after the arrival of Darius in Indus Valley about 500 BCE. The mathematics and devices for time keeping mentioned in these ancient Sanskrit texts, proposes Pingree, such as the water clock may have thereafter arrived in India from Mesopotamia. However, Yukio Ohashi considers this proposal as incorrect, suggesting instead that the Vedic timekeeping efforts, for forecasting appropriate time for rituals, must have begun much earlier and the influence may have flowed from India to Mesopotamia. Ohashi states that it is incorrect to assume that the number of civil days in a year equal 365 in both Hindu and Egyptian–Persian year. Further, adds Ohashi, the Mesopotamian formula is different than Indian formula for calculating time, each can only work for their respective latitude, either would make major errors in predicting time and calendar in the other region. Kim Plofker states that while a flow of timekeeping ideas from either side is plausible, each may have instead developed independently, because the loan-words seen when ideas migrate are missing on both sides as far as words for various time intervals and techniques.
It is hypothesized that there were cultural contacts between the Indian and Greek astronomers via cultural contact with Hellenistic Greece the work of Hipparchus. There were Greek astronomy in Hellenistic period. For example, Suryasiddhanta provides table of sines function which parallel the Hipparchus table of chords, though the Indian calculations are more accurate and detailed. According to Alan Cromer, the Greek influence arrived in India by about 100 BCE; the Indians adopted the Hipparchus system, according to Cromer, it remained that simpler system rather than those made by Ptolemy in the 2nd century. The influence of Greek ideas on early medieval era Indian astronomical theories zodiac symbols, is broadly accepted by scholars. According to Jayant Narlikar, the Vedic literature lacks astrology, the idea of nine planets and any theory that stars or constellation may affect an individual's destiny. One of the manuscripts of the Surya S