A pocket is a bag - or envelope -like receptacle either fastened to or inserted in an article of clothing to hold small items. Pockets are also attached to luggage , backpacks , and similar items. In older usage, a pocket was a separate small bag or pouch.
110-494: Ancient people used leather or cloth pouches to hold valuables. Ötzi (also called the "Iceman"), who lived around 3,300 BCE , had a belt with a pouch sewn to it that contained a cache of useful items: a scraper, drill, flint flake, bone awl, and a dried tinder fungus . In European clothing, fitchets, resembling modern day pockets, appeared in the 13th century. Vertical slits were cut in the super tunic, which did not have any side openings, to allow access to purse or keys slung from
220-562: A Copernican at that time. In a student disputation, he defended heliocentrism from both a theoretical and theological perspective, maintaining that the Sun was the principal source of motive power in the universe. Despite his desire to become a minister in the Lutheran church, he was denied ordination because of beliefs contrary to the Formula of Concord . Near the end of his studies, Kepler
330-718: A lunar eclipse , recording that he remembered being "called outdoors" to see it and that the Moon "appeared quite red". However, childhood smallpox left him with weak vision and crippled hands, limiting his ability in the observational aspects of astronomy. In 1589, after moving through grammar school, Latin school , and seminary at Maulbronn , Kepler attended Tübinger Stift at the University of Tübingen . There, he studied philosophy under Vitus Müller and theology under Jacob Heerbrand (a student of Philipp Melanchthon at Wittenberg ), who also taught Michael Maestlin while he
440-596: A slippery slope scenario in his style guide that, "if we do end by casting aside the AD/BC convention, almost certainly some will argue that we ought to cast aside as well the conventional numbering system [that is, the method of numbering years] itself, given its Christian basis." Some Christians are offended by the removal of the reference to Jesus, including the Southern Baptist Convention . The abbreviation BCE, just as with BC, always follows
550-412: A bright new evening star ( SN 1604 ) appeared, but Kepler did not believe the rumors until he saw it himself. Kepler began systematically observing the supernova. Astrologically, the end of 1603 marked the beginning of a fiery trigon , the start of the about 800-year cycle of great conjunctions ; astrologers associated the two previous such periods with the rise of Charlemagne (c. 800 years earlier) and
660-487: A child. Nevertheless, he often impressed travelers at his grandfather's inn with his phenomenal mathematical faculty. He was introduced to astronomy at an early age and developed a strong passion for it that would span his entire life. At age six, he observed the Great Comet of 1577 , writing that he "was taken by [his] mother to a high place to look at it." In 1580, at age nine, he observed another astronomical event,
770-656: A chronology manuscript, Eclogae Chronicae , from correspondence and earlier work. Upon succession as Holy Roman Emperor, Matthias re-affirmed Kepler's position (and salary) as imperial mathematician but allowed him to move to Linz. In Linz, Kepler's primary responsibilities (beyond completing the Rudolphine Tables ) were teaching at the district school and providing astrological and astronomical services. In his first years there, he enjoyed financial security and religious freedom relative to his life in Prague—though he
880-486: A connection between the cosmos and the individual. He eventually published some of the ideas he had entertained while a student in the Mysterium Cosmographicum (1596), published a little over a year after his arrival at Graz. In December 1595, Kepler was introduced to Barbara Müller, a 23-year-old widow (twice over) with a young daughter, Regina Lorenz, and he began courting her. Müller, an heiress to
990-465: A fake slit sewn shut. If there are pockets they are often much smaller than in men's clothes. Journalists at the Pudding found less than half of women’s front pockets could fit a thin wallet, let alone a phone and keys. A watch pocket or fob pocket is a small pocket designed to hold a pocket watch , sometimes found in men's trousers and waistcoats and in traditional blue jeans . However, due to
1100-489: A fantastic trip to the Moon; it was part allegory, part autobiography, and part treatise on interplanetary travel (and is sometimes described as the first work of science fiction). Years later, a distorted version of the story may have instigated the witchcraft trial against his mother, as the mother of the narrator consults a demon to learn the means of space travel. Following her eventual acquittal, Kepler composed 223 footnotes to
1210-537: A flap or button closure. Camp pockets or cargo pockets are pockets which have been sewn to the outside of the garment. They are usually squared off and are characterized by seaming. A beer pocket is a small pocket within a jacket or vest sized specifically for transporting a bottle of beer . It came into fashion in the 1910s in select areas of the American midwest , prior to Prohibition , after which it faded into relative obscurity before experiencing minor revivals in
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#17327717523491320-648: A generic sense, to refer to "the common era of the Jews". The first use of the phrase "before the common era" may be that in a 1770 work that also uses common era and vulgar era as synonyms, in a translation of a book originally written in German. The 1797 edition of the Encyclopædia Britannica uses the terms vulgar era and common era synonymously. In 1835, in his book Living Oracles , Alexander Campbell , wrote: "The vulgar Era, or Anno Domini;
1430-534: A harsh but legitimate critique of Kepler's system; among a host of objections, Tycho took issue with the use of inaccurate numerical data taken from Copernicus. Through their letters, Tycho and Kepler discussed a broad range of astronomical problems, dwelling on lunar phenomena and Copernican theory (particularly its theological viability). But without the significantly more accurate data of Tycho's observatory, Kepler had no way to address many of these issues. Instead, he turned his attention to chronology and "harmony,"
1540-509: A mathematical relationship that would restore astronomical order. Based on measurements of the aphelion and perihelion of the Earth and Mars, he created a formula in which a planet's rate of motion is inversely proportional to its distance from the Sun. Verifying this relationship throughout the orbital cycle required very extensive calculation; to simplify this task, by late 1602 Kepler reformulated
1650-469: A mathematician to Archduke Ferdinand . To that end, Kepler composed an essay—dedicated to Ferdinand—in which he proposed a force-based theory of lunar motion: "In Terra inest virtus, quae Lunam ciet" ("There is a force in the earth which causes the moon to move"). Though the essay did not earn him a place in Ferdinand's court, it did detail a new method for measuring lunar eclipses, which he applied during
1760-626: A matter of convenience. There is so much interaction between people of different faiths and cultures – different civilizations, if you like – that some shared way of reckoning time is a necessity. And so the Christian Era has become the Common Era. Adena K. Berkowitz, in her application to argue before the United States Supreme Court , opted to use BCE and CE because, "Given the multicultural society that we live in,
1870-404: A model that generally agreed with Tycho's observations to within two arcminutes (the average measurement error). But he was not satisfied with the complex and still slightly inaccurate result; at certain points the model differed from the data by up to eight arcminutes. The wide array of traditional mathematical astronomy methods having failed him, Kepler set about trying to fit an ovoid orbit to
1980-454: A number of treaties dealing with the subject of astrology proper. In his bid to become imperial astronomer, Kepler wrote De Fundamentis (1601), whose full title can be translated as “On Giving Astrology Sounder Foundations”, as a short foreword to one of his yearly almanacs. In this work, Kepler describes the effects of the Sun, Moon, and the planets in terms of their light and their influences upon humors, finalizing with Kepler's view that
2090-715: A period of 138 years in which the traditional BC/AD dating notation was used. BCE/CE is used by the College Board in its history tests, and by the Norton Anthology of English Literature . Others have taken a different approach. The US-based History Channel uses BCE/CE notation in articles on non-Christian religious topics such as Jerusalem and Judaism . The 2006 style guide for the Episcopal Diocese Maryland Church News says that BCE and CE should be used. In June 2006, in
2200-483: A poke". Historically, the term "pocket" referred to a pouch worn around the waist by women in the 17th to 19th centuries, mentioned in the rhyme Lucy Locket . In these pockets, women would carry items needed in their daily lives, such as scissors, pins and needles, and keys. In more modern clothing, while men's clothes generally have pockets, those designed to be worn by women often do not - and sometimes have what are called Potemkin pockets (from Potemkin village ),
2310-522: A position as teacher and district mathematician in Linz . However, Barbara relapsed into illness and died shortly after Kepler's return. Kepler postponed the move to Linz and remained in Prague until Rudolf's death in early 1612, though between political upheaval, religious tension, and family tragedy (along with the legal dispute over his wife's estate), Kepler could do no research. Instead, he pieced together
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#17327717523492420-507: A slit in the outer garment. In the 17th century, pockets began to be sewn into men's clothing, but not women's, which continued to be tied on and hidden under the large skirts popular at the time. The word appears in Middle English as pocket , and is taken from a Norman diminutive of Old French poke , pouque , modern poche , cf. pouch . The form "poke" is now only used in dialect, or in such proverbial sayings as "a pig in
2530-627: A tract against Tycho's (by then deceased) rival, Ursus. In September, Tycho secured him a commission as a collaborator on the new project he had proposed to the emperor: the Rudolphine Tables that should replace the Prutenic Tables of Erasmus Reinhold . Two days after Tycho's unexpected death on 24 October 1601, Kepler was appointed his successor as the imperial mathematician with the responsibility to complete his unfinished work. The next 11 years as imperial mathematician would be
2640-608: A tyrant who persecuted Christians. He numbered years from an initial reference date (" epoch "), an event he referred to as the Incarnation of Jesus. Dionysius labeled the column of the table in which he introduced the new era as " Anni Domini Nostri Jesu Christi " (Of the year of our Lord Jesus Christ]. This way of numbering years became more widespread in Europe with its use by Bede in England in 731. Bede also introduced
2750-488: A unique arrangement of polygons that fit known astronomical observations (even with extra planets added to the system), Kepler began experimenting with 3-dimensional polyhedra . He found that each of the five Platonic solids could be inscribed and circumscribed by spherical orbs ; nesting these solids, each encased in a sphere, within one another would produce six layers, corresponding to the six known planets— Mercury , Venus , Earth , Mars , Jupiter, and Saturn. By ordering
2860-473: A work dismissing astrology altogether (and Roeslin's work in particular). In response to what Kepler saw as the excesses of astrology, on the one hand, and overzealous rejection of it, on the other, Kepler prepared Tertius Interveniens (1610). Nominally this work—presented to the common patron of Roeslin and Feselius—was a neutral mediation between the feuding scholars (the titled meaning "Third-party interventions"), but it also set out Kepler's general views on
2970-480: Is a direct reference to Jesus as Lord . Proponents of the Common Era notation assert that the use of BCE/CE shows sensitivity to those who use the same year numbering system as the one that originated with and is currently used by Christians , but who are not themselves Christian. Former United Nations Secretary-General Kofi Annan has argued: [T]he Christian calendar no longer belongs exclusively to Christians. People of all faiths have taken to using it simply as
3080-556: Is an accepted version of this page Johannes Kepler ( / ˈ k ɛ p l ər / ; German: [joˈhanəs ˈkɛplɐ, -nɛs -] ; 27 December 1571 – 15 November 1630) was a German astronomer , mathematician , astrologer , natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution , best known for his laws of planetary motion , and his books Astronomia nova , Harmonice Mundi , and Epitome Astronomiae Copernicanae , influencing among others Isaac Newton , providing one of
3190-485: Is in particularly common use in Nepal in order to disambiguate dates from the local calendar, Bikram or Vikram Sambat. Disambiguation is needed because the era of the local calendar is quite close to the Common Era. In 2002, an advisory panel for the religious education syllabus for England and Wales recommended introducing BCE/CE dates to schools, and by 2018 some local education authorities were using them. In 2018,
3300-527: Is twice the difference in orb radius. However, Kepler later rejected this formula, because it was not precise enough. Kepler thought the Mysterium had revealed God's geometrical plan for the universe. Much of Kepler's enthusiasm for the Copernican system stemmed from his theological convictions about the connection between the physical and the spiritual ; the universe itself was an image of God, with
3410-422: The Rudolphine Tables in 1623, which at the time was considered his major work. However, due to the publishing requirements of the emperor and negotiations with Tycho Brahe's heir, it would not be printed until 1627. Like Ptolemy , Kepler considered astrology as the counterpart to astronomy, and as being of equal interest and value. However, in the following years, the two subjects drifted apart until astrology
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3520-709: The Epitome is less about Copernicus's work and more about Kepler's own astronomical system. The Epitome contained all three laws of planetary motion and attempted to explain heavenly motions through physical causes. Although it explicitly extended the first two laws of planetary motion (applied to Mars in Astronomia nova ) to all the planets as well as the Moon and the Medicean satellites of Jupiter , it did not explain how elliptical orbits could be derived from observational data. Originally intended as an introduction for
3630-655: The Gregorian calendar without the AD prefix. As early as 1825, the abbreviation VE (for Vulgar Era) was in use among Jews to denote years in the Western calendar. As of 2005 , Common Era notation has also been in use for Hebrew lessons for more than a century. Jews have also used the term Current Era . Some academics in the fields of theology , education , archaeology and history have adopted CE and BCE notation despite some disagreement. A study conducted in 2014 found that
3740-723: The National Trust said it would continue to use BC/AD as its house style. English Heritage explains its era policy thus: "It might seem strange to use a Christian calendar system when referring to British prehistory, but the BC/AD labels are widely used and understood." Some parts of the BBC use BCE/CE, but some presenters have said they will not. As of October 2019, the BBC News style guide has entries for AD and BC, but not for CE or BCE. The style guide for The Guardian says, under
3850-473: The Thirty Years' War . Kepler's belief that God created the cosmos in an orderly fashion caused him to attempt to determine and comprehend the laws that govern the natural world, most profoundly in astronomy. The phrase "I am merely thinking God's thoughts after Him" has been attributed to him, although this is probably a capsulized version of a writing from his hand: Those laws [of nature] are within
3960-550: The University of Tübingen in Württemberg, concerns over Kepler's perceived Calvinist heresies in violation of the Augsburg Confession and the Formula of Concord prevented his return. The University of Padua —on the recommendation of the departing Galileo—sought Kepler to fill the mathematics professorship, but Kepler, preferring to keep his family in German territory, instead travelled to Austria to arrange
4070-614: The date of birth of Jesus . Since the year numbers are the same, BCE and CE dates should be equally offensive to other religions as BC and AD. Roman Catholic priest and writer on interfaith issues Raimon Panikkar argued that the BCE/CE usage is the less inclusive option since they are still using the Christian calendar numbers and forcing it on other nations. In 1993, the English-language expert Kenneth G. Wilson speculated
4180-473: The liberal arts ) and physics (a branch of natural philosophy ). Kepler also incorporated religious arguments and reasoning into his work, motivated by the religious conviction and belief that God had created the world according to an intelligible plan that is accessible through the natural light of reason . Kepler described his new astronomy as "celestial physics", as "an excursion into Aristotle 's Metaphysics ", and as "a supplement to Aristotle's On
4290-458: The marriage problem ). He eventually returned to Reuttinger (the fifth match) who, he wrote, "won me over with love, humble loyalty, economy of household, diligence, and the love she gave the stepchildren." The first three children of this marriage (Margareta Regina, Katharina, and Sebald) died in childhood. Three more survived into adulthood: Cordula (born 1621); Fridmar (born 1623); and Hildebert (born 1625). According to Kepler's biographers, this
4400-442: The numerological relationships among music, mathematics and the physical world, and their astrological consequences. By assuming the Earth to possess a soul (a property he would later invoke to explain how the Sun causes the motion of planets), he established a speculative system connecting astrological aspects and astronomical distances to weather and other earthly phenomena. By 1599, however, he again felt his work limited by
4510-474: The refracting telescope , the Keplerian telescope, which became the foundation of the modern refracting telescope, while also improving on the telescope design by Galileo Galilei , who mentioned Kepler's discoveries in his work. Kepler lived in an era when there was no clear distinction between astronomy and astrology , but there was a strong division between astronomy (a branch of mathematics within
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4620-602: The 10 July eclipse in Graz. These observations formed the basis of his explorations of the laws of optics that would culminate in Astronomiae Pars Optica . On 2 August 1600, after refusing to convert to Catholicism, Kepler and his family were banished from Graz. Several months later, Kepler returned, now with the rest of his household, to Prague. Through most of 1601, he was supported directly by Tycho, who assigned him to analyzing planetary observations and writing
4730-405: The 18.6-year lunar node precession cycle .) Kepler advocates searching for such cycles by gathering observations over a period of many years, "and so far this observation has not been made". Kepler and Helisaeus Roeslin engaged in a series of published attacks and counter-attacks on the importance of astrology after the supernova of 1604; around the same time, physician Philip Feselius published
4840-457: The 1980s and early 2000s. In some of the following illustrations, a folded blue handkerchief is included for illustration purposes: BCE Common Era ( CE ) and Before the Common Era ( BCE ) are year notations for the Gregorian calendar (and its predecessor, the Julian calendar ), the world's most widely used calendar era . Common Era and Before the Common Era are alternatives to
4950-596: The BCE/CE notation is not growing at the expense of BC and AD notation in the scholarly literature, and that both notations are used in a relatively stable fashion. In 2011, media reports suggested that the BC/AD notation in Australian school textbooks would be replaced by BCE/CE notation. The change drew opposition from some politicians and church leaders. Weeks after the story broke, the Australian Curriculum, Assessment and Reporting Authority denied
5060-492: The Bible exegesis and the addition of a simpler, more understandable, description of the Copernican system as well as Kepler's new ideas. Mysterium was published late in 1596, and Kepler received his copies and began sending them to prominent astronomers and patrons early in 1597; it was not widely read, but it established Kepler's reputation as a highly skilled astronomer. The effusive dedication, to powerful patrons as well as to
5170-512: The Catholic Church, as well as the start of the Thirty Years' War , meant that publication of the next two volumes would be delayed. In the interim, and to avoid being subject to the ban, Kepler switched the audience of the Epitome from beginners to that of expert astronomers and mathematicians, as the arguments became more and more sophisticated and required advanced mathematics to be understood. The second volume, consisting of Book IV,
5280-579: The Christian Era, it was sometimes qualified, e.g., "common era of the Incarnation", "common era of the Nativity", or "common era of the birth of Christ". An adapted translation of Common Era into Latin as Era Vulgaris was adopted in the 20th century by some followers of Aleister Crowley , and thus the abbreviation "e.v." or "EV" may sometimes be seen as a replacement for AD. Although Jews have their own Hebrew calendar , they often use
5390-416: The Earth possesses a soul with some sense of geometry. Stimulated by the geometric convergence of rays formed around it, the world-soul is sentient but not conscious. As a shepherd is pleased by the piping of a flute without understanding the theory of musical harmony, so likewise Earth responds to the angles and aspects made by the heavens but not in a conscious manner. Eclipses are important as omens because
5500-485: The Graz school inspectors, Kepler began an ambitious program to extend and elaborate his work. He planned four additional books: one on the stationary aspects of the universe (the Sun and the fixed stars); one on the planets and their motions; one on the physical nature of planets and the formation of geographical features (focused especially on Earth); and one on the effects of the heavens on the Earth, to include atmospheric optics, meteorology, and astrology. He also sought
5610-495: The Gregorian Calendar as BCE and CE without compromising their own beliefs about the divinity of Jesus of Nazareth." In History Today , Michael Ostling wrote: "BC/AD Dating: In the year of whose Lord? The continuing use of AD and BC is not only factually wrong but also offensive to many who are not Christians." Critics note the fact that there is no difference in the epoch of the two systems—chosen to be close to
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#17327717523495720-596: The Heavens " , transforming the ancient tradition of physical cosmology by treating astronomy as part of a universal mathematical physics. Kepler was born on 27 December 1571, in the Free Imperial City of Weil der Stadt (now part of the Stuttgart Region in the German state of Baden-Württemberg ). His grandfather, Sebald Kepler, had been Lord Mayor of the city. By the time Johannes was born,
5830-662: The Kepler family fortune was in decline. His father, Heinrich Kepler, earned a precarious living as a mercenary , and he left the family when Johannes was five years old. He was believed to have died in the Eighty Years' War in the Netherlands. His mother, Katharina Guldenmann , an innkeeper's daughter, was a healer and herbalist . Johannes had six siblings, of which two brothers and one sister survived to adulthood. Born prematurely, he claimed to have been weak and sickly as
5940-576: The Lutherans against Kepler. His first publication in Linz was De vero Anno (1613), an expanded treatise on the year of Christ's birth. He also participated in deliberations on whether to introduce Pope Gregory 's reformed calendar to Protestant German lands. On 30 October 1613, Kepler married Susanna Reuttinger. Following the death of his first wife Barbara, Kepler had considered 11 different matches over two years (a decision process formalized later as
6050-542: The Mars data (the Vicarious Hypothesis ), Kepler immediately concluded that all planets move in ellipses, with the Sun at one focus —his first law of planetary motion. Because he employed no calculating assistants, he did not extend the mathematical analysis beyond Mars. By the end of the year, he completed the manuscript for Astronomia nova , though it would not be published until 1609 due to legal disputes over
6160-657: The Sun corresponding to the Father, the stellar sphere to the Son , and the intervening space between them to the Holy Spirit . His first manuscript of Mysterium contained an extensive chapter reconciling heliocentrism with biblical passages that seemed to support geocentrism. With the support of his mentor Michael Maestlin, Kepler received permission from the Tübingen university senate to publish his manuscript, pending removal of
6270-625: The United States, the Kentucky State School Board reversed its decision to use BCE and CE in the state's new Program of Studies, leaving education of students about these concepts a matter of local discretion. The use of CE in Jewish scholarship was historically motivated by the desire to avoid the implicit "Our Lord" in the abbreviation AD . Although other aspects of dating systems are based in Christian origins, AD
6380-607: The analysis, under Tycho's direction, of the orbit of Mars. In this work Kepler introduced the revolutionary concept of planetary orbit, a path of a planet in space resulting from the action of physical causes, distinct from previously held notion of planetary orb (a spherical shell to which planet is attached). As a result of this breakthrough astronomical phenomena came to be seen as being governed by physical laws. Kepler calculated and recalculated various approximations of Mars's orbit using an equant (the mathematical tool that Copernicus had eliminated with his system), eventually creating
6490-407: The animal faculty of the Earth is violently disturbed by the sudden intermission of light, experiencing something like emotion and persisting in it for some time. Kepler surmises that the Earth has "cycles of humors" as living animals do, and gives for an example that "the highest tides of the sea are said by sailors to return after nineteen years around the same days of the year". (This may refer to
6600-490: The astronomer Tycho Brahe in Prague , and eventually the imperial mathematician to Emperor Rudolf II and his two successors Matthias and Ferdinand II . He also taught mathematics in Linz , and was an adviser to General Wallenstein . Additionally, he did fundamental work in the field of optics , being named the father of modern optics, in particular for his Astronomiae pars optica . He also invented an improved version of
6710-509: The birth of Christ (c. 1600 years earlier), and thus expected events of great portent, especially regarding the emperor. It was in this context, as the imperial mathematician and astrologer to the emperor, that Kepler described the new star two years later in his De Stella Nova . In it, Kepler addressed the star's astronomical properties while taking a skeptical approach to the many astrological interpretations then circulating. He noted its fading luminosity, speculated about its origin, and used
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#17327717523496820-586: The data. In Kepler's religious view of the cosmos, the Sun (a symbol of God the Father ) was the source of motive force in the Solar System. As a physical basis, Kepler drew by analogy on William Gilbert 's theory of the magnetic soul of the Earth from De Magnete (1600) and on his own work on optics. Kepler supposed that the motive power (or motive species ) radiated by the Sun weakens with distance, causing faster or slower motion as planets move closer or farther from it. Perhaps this assumption entailed
6930-419: The decline in popularity of pocket watches, these pockets are rarely used for their original intended purpose. A besom pocket or slit pocket is a pocket cut into a garment instead of being sewn on. These pockets often have reinforced piping along the slit of the pocket, appearing perhaps as an extra piece of fabric or stitching. Besom pockets are found on a tuxedo jacket or trousers and may be accented with
7040-618: The difficulties of the over-extended imperial treasury meant that actually getting hold of enough money to meet financial obligations was a continual struggle. Partly because of financial troubles, his life at home with Barbara was unpleasant, marred with bickering and bouts of sickness. Court life, however, brought Kepler into contact with other prominent scholars ( Johannes Matthäus Wackher von Wackhenfels , Jost Bürgi , David Fabricius , Martin Bachazek, and Johannes Brengger, among others) and astronomical work proceeded rapidly. In October 1604,
7150-468: The early 20th century. The phrase "common era", in lower case , also appeared in the 19th century in a "generic" sense, not necessarily to refer to the Christian Era, but to any system of dates in common use throughout a civilization. Thus, "the common era of the Jews", "the common era of the Mahometans", "common era of the world", "the common era of the foundation of Rome". When it did refer to
7260-496: The emperor sought Kepler's advice in times of political trouble. Rudolf was actively interested in the work of many of his court scholars (including numerous alchemists ) and kept up with Kepler's work in physical astronomy as well. Officially, the only acceptable religious doctrines in Prague were Catholic and Utraquist , but Kepler's position in the imperial court allowed him to practice his Lutheran faith unhindered. The emperor nominally provided an ample income for his family, but
7370-428: The entry for CE/BCE: "some people prefer CE (common era, current era, or Christian era) and BCE (before common era, etc.) to AD and BC, which, however, remain our style". In the United States, the use of the BCE/CE notation in textbooks was reported in 2005 to be growing. Some publications have transitioned to using it exclusively. For example, the 2007 World Almanac was the first edition to switch to BCE/CE, ending
7480-449: The estates of her late husbands, was also the daughter of a successful mill owner. Her father Jobst initially opposed a marriage. Even though Kepler had inherited his grandfather's nobility, Kepler's poverty made him an unacceptable match. Jobst relented after Kepler completed work on Mysterium , but the engagement nearly fell apart while Kepler was away tending to the details of publication. However, Protestant officials—who had helped set up
7590-528: The foundations for his theory of universal gravitation . The variety and impact of his work made Kepler one of the founders and fathers of modern astronomy , the scientific method , natural and modern science . He has been described as the "father of science fiction " for his novel Somnium . Kepler was a mathematics teacher at a seminary school in Graz , where he became an associate of Prince Hans Ulrich von Eggenberg . Later he became an assistant to
7700-486: The fourth year of Jesus Christ, the first of which was but eight days", and also refers to the common era as a synonym for vulgar era with "the fact that our Lord was born on the 4th year before the vulgar era, called Anno Domini, thus making (for example) the 42d year from his birth to correspond with the 38th of the common era". The Catholic Encyclopedia (1909) in at least one article reports all three terms (Christian, Vulgar, Common Era) being commonly understood by
7810-405: The girdle of the tunic. According to historian Rebecca Unsworth, it was in the late 15th century that pockets became more noticeable. During the 16th century, pockets increased in popularity and prevalence. In slightly later European clothing, pockets began by being hung like purses from a belt, which could be concealed beneath a coat or jerkin to discourage pickpocketing and reached through
7920-540: The grasp of the human mind; God wanted us to recognize them by creating us after his own image so that we could share in his own thoughts. Kepler advocated for tolerance among Christian denominations, for example arguing that Catholics and Lutherans should be able to take communion together. He wrote, "Christ the Lord neither was nor is Lutheran, nor Calvinist, nor Papist." Kepler's first major astronomical work, Mysterium Cosmographicum ( The Cosmographic Mystery , 1596),
8030-542: The inaccuracy of available data—just as growing religious tension was also threatening his continued employment in Graz. In December of that year, Tycho invited Kepler to visit him in Prague ; on 1 January 1600 (before he even received the invitation), Kepler set off in the hopes that Tycho's patronage could solve his philosophical problems as well as his social and financial ones. On 4 February 1600, Kepler met Tycho Brahe and his assistants Franz Tengnagel and Longomontanus at Benátky nad Jizerou (35 km from Prague),
8140-515: The lack of observed parallax to argue that it was in the sphere of fixed stars, further undermining the doctrine of the immutability of the heavens (the idea accepted since Aristotle that the celestial spheres were perfect and unchanging). The birth of a new star implied the variability of the heavens. Kepler also attached an appendix where he discussed the recent chronology work of the Polish historian Laurentius Suslyga ; he calculated that, if Suslyga
8250-405: The life of Jesus . Around 1611, Kepler circulated a manuscript of what would eventually be published (posthumously) as Somnium [The Dream]. Part of the purpose of Somnium was to describe what practicing astronomy would be like from the perspective of another planet, to show the feasibility of a non-geocentric system. The manuscript, which disappeared after changing hands several times, described
8360-515: The match—pressured the Müllers to honor their agreement. Barbara and Johannes were married on 27 April 1597. In the first years of their marriage, the Keplers had two children (Heinrich and Susanna), both of whom died in infancy. In 1602, they had a daughter (Susanna); in 1604, a son (Friedrich); and in 1607, another son (Ludwig). Following the publication of Mysterium and with the blessing of
8470-418: The men who controlled his position in Graz, also provided a crucial doorway into the patronage system . In 1621, Kepler published an expanded second edition of Mysterium , half as long again as the first, detailing in footnotes the corrections and improvements he had achieved in the 25 years since its first publication. In terms of impact, the Mysterium can be seen as an important first step in modernizing
8580-423: The mid-19th century by Jewish religious scholars. Since the late 20th century, BCE and CE have become popular in academic and scientific publications on the grounds that BCE and CE are religiously neutral terms. They have been promoted as more sensitive to non-Christians by not referring to Jesus , the central figure of Christianity , especially via the religious terms " Christ " and Dominus ("Lord") used by
8690-459: The most productive of his life. Kepler's primary obligation as imperial mathematician was to provide astrological advice to the emperor. Though Kepler took a dim view of the attempts of contemporary astrologers to precisely predict the future or divine specific events, he had been casting well-received detailed horoscopes for friends, family, and patrons since his time as a student in Tübingen. In addition to horoscopes for allies and foreign leaders,
8800-504: The opinions of many of the astronomers to whom he had sent Mysterium , among them Reimarus Ursus (Nicolaus Reimers Bär)—the imperial mathematician to Rudolf II and a bitter rival of Tycho Brahe . Ursus did not reply directly, but republished Kepler's flattering letter to pursue his priority dispute over (what is now called) the Tychonic system with Tycho. Despite this black mark, Tycho also began corresponding with Kepler, starting with
8910-676: The original Anno Domini (AD) and Before Christ (BC) notations used for the same calendar era. The two notation systems are numerically equivalent: "2024 CE" and "AD 2024" each describe the current year; "400 BCE" and "400 BC" are the same year. The expression can be traced back to 1615, when it first appears in a book by Johannes Kepler as the Latin : annus aerae nostrae vulgaris ( year of our common era ), and to 1635 in English as " Vulgar Era". The term "Common Era" can be found in English as early as 1708, and became more widely used in
9020-470: The other abbreviations. Nevertheless, its epoch remains the same as that used for the Anno Domini era. The idea of numbering years beginning from the date that he believed to be the date of birth of Jesus , was conceived around the year 525 by the Christian monk Dionysius Exiguus . He did this to replace the then dominant Era of Martyrs system, because he did not wish to continue the memory of
9130-422: The practice of dating years before what he supposed was the year of birth of Jesus, without a year zero . In 1422, Portugal became the last Western European country to switch to the system begun by Dionysius. The term "Common Era" is traced back in English to its appearance as " Vulgar Era" to distinguish years of the Anno Domini era, which was in popular use, from dates of the regnal year (the year of
9240-491: The proportion in terms of geometry: planets sweep out equal areas in equal times —his second law of planetary motion. He then set about calculating the entire orbit of Mars, using the geometrical rate law and assuming an egg-shaped ovoid orbit. After approximately 40 failed attempts, in late 1604 he at last hit upon the idea of an ellipse, which he had previously assumed to be too simple a solution for earlier astronomers to have overlooked. Finding that an elliptical orbit fit
9350-547: The reader by diverging too much from Ptolemy." Modern astronomy owes much to Mysterium Cosmographicum , despite flaws in its main thesis, "since it represents the first step in cleansing the Copernican system of the remnants of the Ptolemaic theory still clinging to it." The extended line of research that culminated in Astronomia Nova ( A New Astronomy )—including the first two laws of planetary motion —began with
9460-507: The reign of a sovereign) typically used in national law. (The word 'vulgar' originally meant 'of the ordinary people', with no derogatory associations. ) The first use of the Latin term anno aerae nostrae vulgaris may be that in a 1615 book by Johannes Kepler . Kepler uses it again, as ab Anno vulgaris aerae , in a 1616 table of ephemerides , and again, as ab anno vulgaris aerae , in 1617. A 1635 English edition of that book has
9570-595: The rumours and stated that the BC/AD notation would remain, with CE and BCE as an optional suggested learning activity. In 2013, the Canadian Museum of Civilization (now the Canadian Museum of History) in Gatineau (opposite Ottawa ), which had previously switched to BCE/CE, decided to change back to BC/AD in material intended for the public while retaining BCE/CE in academic content. The notation
9680-429: The site where Tycho's new observatory was being constructed. Over the next two months, he stayed as a guest, analyzing some of Tycho's observations of Mars; Tycho guarded his data closely, but was impressed by Kepler's theoretical ideas and soon allowed him more access. Kepler planned to test his theory from Mysterium Cosmographicum based on the Mars data, but he estimated that the work would take up to two years (since he
9790-419: The solids selectively— octahedron , icosahedron , dodecahedron , tetrahedron , cube —Kepler found that the spheres could be placed at intervals corresponding to the relative sizes of each planet's path, assuming the planets circle the Sun. Kepler also found a formula relating the size of each planet's orb to the length of its orbital period : from inner to outer planets, the ratio of increase in orbital period
9900-523: The stars, except in general statements to discourage drastic action). However, it was clear that Kepler's future prospects in the court of Matthias were dim. Also in that year, Barbara Kepler contracted Hungarian spotted fever , then began having seizures . As Barbara was recovering, Kepler's three children all fell sick with smallpox; Friedrich, 6, died. Following his son's death, Kepler sent letters to potential patrons in Württemberg and Padua . At
10010-530: The story—several times longer than the actual text—which explained the allegorical aspects as well as the considerable scientific content (particularly regarding lunar geography) hidden within the text. In 1611, the growing political-religious tension in Prague came to a head. Emperor Rudolf—whose health was failing—was forced to abdicate as King of Bohemia by his brother Matthias . Both sides sought Kepler's astrological advice, an opportunity he used to deliver conciliatory political advice (with little reference to
10120-451: The theory proposed by Copernicus in his De revolutionibus orbium coelestium . While Copernicus sought to advance a heliocentric system in this book, he resorted to Ptolemaic devices (viz., epicycles and eccentric circles) in order to explain the change in planets' orbital speed, and also continued to use as a point of reference the center of the Earth's orbit rather than that of the Sun "as an aid to calculation and in order not to confuse
10230-492: The title page in English that may be the earliest-found use of Vulgar Era in English. A 1701 book edited by John Le Clerc includes the phrase "Before Christ according to the Vulgar Æra, 6". The Merriam Webster Dictionary gives 1716 as the date of first use of the term "vulgar era" (which it defines as Christian era). The first published use of "Christian Era" may be the Latin phrase annus aerae christianae on
10340-480: The title page of a 1584 theology book, De Eucharistica controuersia . In 1649, the Latin phrase annus æræ Christianæ appeared in the title of an English almanac. A 1652 ephemeris may be the first instance found so far of the English use of "Christian Era". The English phrase "Common Era" appears at least as early as 1708, and in a 1715 book on astronomy it is used interchangeably with "Christian Era" and "Vulgar Era". A 1759 history book uses common æra in
10450-497: The traditional Jewish designations – B.C.E. and C.E. – cast a wider net of inclusion." In the World History Encyclopedia , Joshua J. Mark wrote "Non-Christian scholars, especially, embraced [CE and BCE] because they could now communicate more easily with the Christian community. Jewish, Islamic, Hindu and Buddhist scholars could retain their [own] calendar but refer to events using
10560-403: The uninitiated, Kepler sought to model his Epitome after that of his master Michael Maestlin , who published a well-regarded book explaining the basics of geocentric astronomy to non-experts. Kepler completed the first of three volumes, consisting of Books I–III, by 1615 in the same question-answer format of Maestlin's and have it printed in 1617. However, the banning of Copernican books by
10670-480: The use of Tycho's observations, the property of his heirs. Since completing the Astronomia Nova , Kepler had intended to compose an astronomy textbook that would cover all the fundamentals of heliocentric astronomy . Kepler spent the next several years working on what would become Epitome Astronomiae Copernicanae ( Epitome of Copernican Astronomy ). Despite its title, which merely hints at heliocentrism,
10780-399: The value of astrology, including some hypothesized mechanisms of interaction between planets and individual souls. While Kepler considered most traditional rules and methods of astrology to be the "evil-smelling dung" in which "an industrious hen" scrapes, there was an "occasional grain-seed, indeed, even a pearl or a gold nugget" to be found by the conscientious scientific astrologer. Kepler
10890-672: The year number. Unlike AD, which still often precedes the year number, CE always follows the year number (if context requires that it be written at all). Thus, the current year is written as 2024 in both notations (or, if further clarity is needed, as 2024 CE, or as AD 2024), and the year that Socrates died is represented as 399 BCE (the same year that is represented by 399 BC in the BC/AD notation). The abbreviations are sometimes written with small capital letters, or with periods (e.g., " B.C.E. " or "C.E."). The US-based Society of Biblical Literature style guide for academic texts on religion prefers BCE/CE to BC/AD. Johannes Kepler This
11000-463: Was a much happier marriage than his first. On 8 October 1630, Kepler set out for Regensburg, hoping to collect interest on work he had done previously. A few days after reaching Regensburg, Kepler became sick, and progressively became worse. On 15 November 1630, just over a month after his arrival, he died. He was buried in a Protestant churchyard in Regensburg that was completely destroyed during
11110-513: Was a student, until he became Chancellor at Tübingen in 1590. He proved himself to be a superb mathematician and earned a reputation as a skillful astrologer, casting horoscopes for fellow students. Under the instruction of Michael Maestlin, Tübingen's professor of mathematics from 1583 to 1631, he learned both the Ptolemaic system and the Copernican system of planetary motion. He became
11220-559: Was convinced "that the geometrical things have provided the Creator with the model for decorating the whole world". In Harmonice Mundi (1619), he attempted to explain the proportions of the natural world—particularly the astronomical and astrological aspects—in terms of music. The central set of "harmonies" was the musica universalis or "music of the spheres", which had been studied by Pythagoras , Ptolemy and others before Kepler; in fact, soon after publishing Harmonice Mundi , Kepler
11330-459: Was correct that accepted timelines were four years behind, then the Star of Bethlehem —analogous to the present new star—would have coincided with the first great conjunction of the earlier 800-year cycle. Over the following years, Kepler attempted (unsuccessfully) to begin a collaboration with Italian astronomer Giovanni Antonio Magini , and dealt with chronology, especially the dating of events in
11440-408: Was embroiled in a priority dispute with Robert Fludd , who had recently published his own harmonic theory. Kepler began by exploring regular polygons and regular solids , including the figures that would come to be known as Kepler's solids . From there, he extended his harmonic analysis to music, meteorology, and astrology; harmony resulted from the tones made by the souls of heavenly bodies—and in
11550-481: Was excluded from Eucharist by his Lutheran church over his theological scruples. It was also during his time in Linz that Kepler had to deal with the accusation and ultimate verdict of witchcraft against his mother Katharina in the Protestant town of Leonberg . That blow, happening only a few years after Kepler's excommunication , is not seen as a coincidence but as a symptom of the full-fledged assault waged by
11660-499: Was no longer practiced among professional astronomers. Sir Oliver Lodge observed that Kepler was somewhat disdainful of astrology in his own day, as he was "continually attacking and throwing sarcasm at astrology, but it was the only thing for which people would pay him, and on it after a fashion he lived." Nonetheless, Kepler spent a huge amount of time trying to restore astrology on a firmer philosophical footing, composing numerous astrological calendars, more than 800 nativities, and
11770-664: Was not allowed to simply copy the data for his own use). With the help of Johannes Jessenius , Kepler attempted to negotiate a more formal employment arrangement with Tycho, but negotiations broke down in an angry argument and Kepler left for Prague on 6 April. Kepler and Tycho soon reconciled and eventually reached an agreement on salary and living arrangements, and in June, Kepler returned home to Graz to collect his family. Political and religious difficulties in Graz dashed his hopes of returning immediately to Brahe; in hopes of continuing his astronomical studies, Kepler sought an appointment as
11880-425: Was published in 1620, followed by the third volume, consisting of Books V–VII, in 1621. In the years following the completion of Astronomia Nova , most of Kepler's research was focused on preparations for the Rudolphine Tables and a comprehensive set of ephemerides (specific predictions of planet and star positions) based on the table, though neither would be completed for many years. Kepler, at last, completed
11990-716: Was recommended for a position as teacher of mathematics and astronomy at the Protestant school in Graz. He accepted the position in April 1594, at the age of 22. Before concluding his studies at Tübingen, Kepler accepted an offer to teach mathematics as a replacement to Georg Stadius at the Protestant school in Graz (now in Styria, Austria). During this period (1594–1600), he issued many official calendars and prognostications that enhanced his reputation as an astrologer. Although Kepler had mixed feelings about astrology and disparaged many customary practices of astrologers, he believed deeply in
12100-420: Was the first published defense of the Copernican system. Kepler claimed to have had an epiphany on 19 July 1595, while teaching in Graz , demonstrating the periodic conjunction of Saturn and Jupiter in the zodiac : he realized that regular polygons bound one inscribed and one circumscribed circle at definite ratios, which, he reasoned, might be the geometrical basis of the universe. After failing to find
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