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ANCIENT CHINESE ASTRONOMY. INHABITED WORLD CALLED “TIANXIA” AREAS OF ASTRONOMICAL INTEREST “LIFA” – CALENDRICAL METHODS – MEASUREMENT AND MASTERY OF REGULAR ASTRONOMICAL MOVEMENTS
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ANCIENT CHINESE ASTRONOMY • INHABITED WORLD CALLED “TIANXIA” • AREAS OF ASTRONOMICAL INTEREST • “LIFA” – CALENDRICAL METHODS – MEASUREMENT AND MASTERY OF REGULAR ASTRONOMICAL MOVEMENTS • “TIANWEN” – CELESTIAL PATTERNS – STUDIES IN WHICH ONE OBSERVED UNPREDICTABLE ASTRONOMICAL PHENOMENA AND INTERPRETING THE IMPORTANCE OF THESE PHENOMENA TO HUMANS
ANCIENT CHINESE ASTRONOMY • PRACTITIONERS OF BOTH LIFA AND TIANWEN WERE PERSONS OF IMPORTANCE – ON THE EMPEROR’S STAFF • TIAN (HEAVEN) WAS IN IMPERSONAL ENTITY WHOSE WILL IT WAS THAT ORDER IN THE WORLD SHOULD BE MAINTAINED. IF ORDER WAS DISRUPTED, FAMINE, PLAGUES AND OTHER DISASTERS MIGHT OCCUR. • THE TIANWEN WERE THE PRACTIONERS WHO ADDRESSES SUCH ISSUES. • LIFA SPECIALISTS STUDIED REGULAR ASTRONOMICAL MOTIONS SO THE EMPEROR COULD CONSTRUCT AN ALMANAC THAT DEMONSTRATED THE ORDER OF HIS RULE. STARTING WITH EMPEROR WU OF THE HAN DYNESTY IN 104 BC THERE WERE 47 SUCH SYSTEMS GENERATED. • EVERY SYSTEM REQUIRED A LUNI-SOLAR CALENDAR (12 LUNAR MONTHS PER YEAR + AN INTERCALARY MONTH AS NEEDED) • THE INTERCALARY MONTH WAS CALLED “RUN YUE”. • MONTHS BEGAN WITH NEW MOON • THE WINTER SOLSTICE WAS THE BASIC MARK POINT OF THE SEASONS. • THEY WERE ABLE TO PREDICT THE MOTIONS OF THE PLANETS AND THE OCCURRENCE OF LUNAR ECLIPSES BUT NOT SOLAR ECLIPSES. • SOLAR ECLIPSES BELONGED TO THE DOMAIN OF THE TIANWEN
ANCIENT CHINESE ASTRONOMY • LIFA SPECIALISTS USED NUMERICAL RATHER THAN GEOMETRIC MATHEMATICS • THE ACTIVITIES OF TIANWEN SPECIALISTS TRACE BACK AS FAR AS THE 2ND MILLENIUM BC • THEY WERE INTERESTED IN METEOR SHOWERS, COMETS, SOLAR ECLIPSES, SUNSPOTS, NOVAE, AURORAE, ETC. • THEY HAD ACCESS TO SOPHISTICATED ARMILLARY SHPERES AND KNEW THE HEAVENS AS WELL AS ANY ANCIENT ASTRONOMERS UP TO THE TIME OF TYCHO BRAHE
ANCIENT CHINESE COSMOLOGY • THE INHABITED WORLD WAS A SMALL REGION NEAR THE CENTER OF A FLAT EARTH • IT WAS LOCATED ON A DIAMETRIC PLANE AT THE CENTER OF A CELESTIAL SPHERE • THE SPHERE ROTATED ON AN INCLINED AXIS • CELESTIAL BODIES MOVED ON THE INNER SURFACE OF THIS SPHERE
ANCIENT CHINESE ASTRONOMY • CRAB SUPERNOVA • A NAKED EYE OBJECT • OCCURRED IN 1054 AD • OBSERVED BY TWO TIANWEN ASTRONOMERS WHO ANNOUNCED TO THE EMPEROR THAT THIS EVENT BODE GREAT THINGS FOR HIS RULE • HE HAD THEM BEHEADED • ALSO OBSERVED BY ARABIAN ASTRONOMERS • NOT RECORDED IN EUROPEAN ANNALS
ARABIC AND ISLAMIC ASTRONOMY • AS ROMAN RULE DECLINED ARABIAN ASTRONOMY BECAME MORE IMPORTANT • ST. EPHREM FOUNDED A SCHOOL IN EDESSA IN MESOPOTAMIA CIRCA 350 AD. • THEY TRANSLATED MANY OF THE GREEK TEXTS INTO SYRIAC • LATER THE SCHOOL MOVED TO JUNDISHAPUR WHERE CHRISTIAN PHYSICIANS HELPED THEM TRANSLATE GREEK MEDICAL TEXTS TO SYRIAC. • UPON DISCOVERING THE TREASURE OF OTHER GREEK MANUSCRIPTS HARUN AL-RASHID (CALIPH IN 786) SENT AGENTS TO BUY GREEK MANUSCRIPTS. • CALIPH AL-MA’MUN ESTABLISHED THE “HOUSE OF WISDOM” IN BAGHDAD WHERE THE CHRISTIAN HUNAYN IBN ISHAQ AL-IBADI HELPED TRANSLATE GREEK WORKS INTO ARABIC AND SYRIAC • THE SPREAD OF ISLAM INSURED THAT A WIDE RANGE OF PEOPLES WOULD UNDERSTAND THE TEXTS WRITTEN IN ARABIC. • MANY OF THESE WORKS WERE LATER TRANSLATED BACK INTO LATIN AND GREEK AND, EVEN THOUGH THEY MAY HAVE SUFFERED DUE TO MULTIPLE TRANSLATIONS, IN MANY CASES THESE ARE THE ONLY COPIES OF THE ORIGINAL WORKS.
CHALLENGES OF ISLAM TO ASTRONOMY I. THE LUNAR CALENDAR • MOHAMMED TAUGHT AGAINST INTERCALARY MONTHS • THIS MADE THE CALENDAR YEAR ABOUT 11 DAYS SHORT OF THE SEASONAL YEAR • EACH MONTH BEGAN WITH THE FIRST SIGHTING OF THE WAXING CRESCENT MOON IN THE WESTERN SKY SO NEIGHBORING TOWNS COULD RECKON THE BEGINNING OF A MONTH DIFFERENTLY. • RAMADAN, UNLIKE MANY OTHER RELIGIOUS HOLIDAYS (LIKE EASTER), COULD OCCUR DURING ANY SEASON
CHALLENGES OF ISLAM TO ASTRONOMY • PRAYER TIMES ARE SET TO BE AT: SUNSET, NIGHTFALL, DAYBREAK, MIDDAY AND AFTERNOON. A. TIMES VARIED WITH LATITUDE AND LONGITUDE B. MUWAQQITS (TIMEKEEPERS) WERE INSTITUTED IN MOSQUES WHEN THE BASIC TRIGONOMETRIC FUNCTIONS WERE DEVELOPED. C. ASTRONOMY BECAME A NOBLE PROFESSION AND THE QUALITY OF ASTRONOMICAL OBSERVATIONS IMPROVED MARKEDLY. D. ASTROLOGY WAS (AND IS) DETESTED BY ISLAM
CHALLENGES OF ISLAM TO ASTRONOMY • MOSQUES HAD TO BE ORIENTED TOWARD MECCA AND YOU NEED TO FACE MECCA WHEN PRAYING (DO YOU ORIENT IT AS IF TRAVELING ALONG A GREAT CIRCLE?) A. EARLY SPANISH MOSQUES SIMPLY FACED SOUTH B. “QIBLA”, THE SACRED ORIENTATION, WAS OCCASIONALLY ASSUMED TO BE THE DIRECTION TOWARD WHICH PILGRIMS HEADED FOR MECCA STARTED C. WHEN SPHERICAL GEOMETRY WAS PERFECTED TABLES WERE GENERATED TO DICTATE WHAT DIRECTION A MOSQUE SHOULD BE ORIENTED GIVEN ITS LATITUDE AND LONGITUDE.
DEVELOPMENT OF ISLAMIC ASTRONOMY • PTOLEMY’S ALMAGEST GAVE THEM A MODEL TO EMULATE • BETTER OBSERVATIONS WERE NEEDED • OBSERVER’S WERE LARGELY ASTROLOGERS WHO WERE CONDEMNED BY ISLAM AS “FORTUNE TELLERS”. • HOWEVER THEIR OBSERVATIONS WERE VALUED AND USED. • GOOD OBSERVATORIES WERE LARGE AND NEEDED FIXED FACILITIES (THE START OF WHAT WE CALL “OBSERVATORY”) • SEVERAL OBSERVATORIES WERE BUILT BY RULERS OR RICH PATRONS BUT FAILED WHEN THE RELIGIOUS LEADERS HAD THEM KILLED. • VIZIER OF THE FATAMID CALIPH ORDERED CONSTRUCTION OF AN OBSERVATORY IN 1120. HE WAS KILLED BUT THE CONSTRUCTION CONTINUED UNTIL 1125 WHEN THE NEW VIZIER WAS KILLED FOR “COMMUNICATING WITH SATURN” AND THE OBSERVATORY WAS DEMOLISHED. • AN OBSERVATORY WAS BUILT IN ISTAMBUL IN 1575 (CONTEMPORARY WITH TYCHO). THE ASTRONOMER TAQI AL-DIN OBSERVED A BRIGHT COMET IN 1577 WHICH HE INTERPRETED AS A POSITIVE SIGN TO THE SULTAN. HOWEVER MISFORTUNE FOLLOWED. IN 1580 THE SULTAN HAD THE OBSERVATORY DEMOLISHED AS THE URGING OF THE RELIGIOUS LEADERS.
DEVELOPMENT OF ISLAMIC ASTRONOMY 1. TWO SUCCESSFUL OBSERVATORIES • MARAGHA – NORTHERN IRAN • BUILT BY HULAGU, MONGOL RULER OF PERSIA, WHO LIKED ASTROLOGY • CHIEF ASTRONOMER WAS NASIR AL-DIN AL-TUSI • CONSTRUCTION BEGAN IN 1259 • GENERATED TABLES CALLED “ZIJ” • INSTRUMENTS • MURAL QUADRANT (MEASURED ALTITUDES) – 14 FOOT RADIUS • ARMILLARY SPHERE (FIVE FOOT RADIUS) • THE OBSERVATORY CLOSED WHEN AL-TUSI DIED IN 1274
DEVELOPMENT OF ISLAMIC ASTRONOMY • IN 1447 AN OBSERVATORY WAS BUILT AT SAMARKAND IN CENTRAL ASIA A. BUILT BY ULUGH BEG, GRANDSON OF TAMARLANE IN 1420. B. PRIMARY INSTRUMENT WAS A TRANSIT INSTRUMENT IN THE FORM OF A SEXTANT C. IT WAS OVER 130 FEET IN RADIUS D. DEVELOPED A CATALOG OF OVER 1,000 STARS E. THESE UNIQUE OBSERVATIONS ARE CONSIDERED TO BE THE ONE IMPORTANT STAR CATALOG OF THE MIDDLE AGES. F. IN 1449 ULUGH BEG WAS MURDERED AND THE OBSERVATORY WAS CLOSED.
ARABIC PLANETARY ASTRONOMY • IN 770 A ZIJ (ASTRONOMICAL TABLE) WAS COMPOSED IN BAGHDAD BY AL-KHWARIZMI. • MANY OF THE DATA DERIVED FROM DOCUMENTS BROUGHT THERE FROM INDIA • ANOTHER ZIJ WAS GENERATED IN THE EARLY 900’S AD BY MUHAMMAD AL-BATTANI. IT WAS TRANSLATED INTO LATIN AND USED EXTENSIVELY BY COPERNICUS. • ABD AL-RAHMAN AL-SUFI, A TENTH-CENTURY ASTRONOMER, WROTE, BOOK ON THE CONSTELLATION OF FIXED STARS. HOWEVER HIS MEASUREMENTS WERE LARGELY INACCURATE EVEN THOUGH THEY HAD THE ASTROLABE. THEY WERE MORE INTERESTED IN THE PLANETS THAN THE STARS. • AL-SUFI AND THABIT IBN QURRA HAD SHUKUK (DOUBTS) CONCERNING PTOLEMY’S MODEL. • PTOLEMEY’S EQUANT WAS HEAVILY CRITICIZED.
ARABIC PLANETARY ASTRONOMY • IN THE 12TH CENTURY, MUHAMMAD IBN RUSHD (KNOWN AS “THE COMMENTATOR”) REJECTED PTOLEMY’S MODELS AND PROPOSED CONCENTRIC SPHERES. • HIS IDEAS WERE GROSSLY INACCURATE • ECCENTRIC SPHERES WERE LESS OBJECTIONABLE THAN EQUANTS BUT STILL REGARDED AS UNSATISFACTORY • IBN AL-SHATIR, MUWAQQIT OF THE UMAYYAD MOSQUE IN DAMASCUS PROPOSED AN EPICYCLE SYSTEM WITH THE EARTH AT THE TRUE CENTER. • HE ADDED A SECOND EPICYCLE WHICH MOVED WESTWARD (CLOCKWISE) ON THE PRIMARY EPICYCLE WHICH MOVED EASTWARD AT THE RATE OF THE “MEAN” MOON ON THE DEFERENT. THE MOON MOVED ON THE EASTWARD ON THE SECOND EPICYCLE.
THE ASTROLABE • DEVELOPMENT BEGAN AS EARLY AS 150 BC • PERFECTED BY ISLAMIC ASTRONOMERS BETWEEN 800 AND 1200 AD • USES • DETERMINE CURRENT TIME BASED ON THE ELEVATION (ALTITUDE) OF A STAR • PREDICT THE TIME OF A FUTURE ASTRONOMICAL EVENT, SUCH AS SUNRISE, MOON RISE, ETC. • FOUR KINDS • PLANISPHERIC • MOST WIDELY USED • A PROJECTION OF THE SPHERICAL ASTROLABE ONTO A PLANE • LINEAR • SPHERICAL • MARINER’S (A PRECURSOR TO THE MODERN DAY SEXTANT)
