Presentation on theme: "Armillary Spheres NASS Montreal 2001 Roger Bailey"— Presentation transcript:
1Armillary Spheres NASS Montreal 2001 Roger Bailey When I travel, I like to enjoy sunsets and search for sundials. This year we enjoyed the sunsets at Cabo Carvoeiro on the Algarve Coast of Portugal. This was our base for searching for sundials
2Armillary Spheres in Portugal Armillary spheres are everywhere!Traffic circle/ fountainFlag, money, coat of armsChurches, monasteries, convents, schools, monuments, flagpolesWhat is an armillary sphere and why is it the symbol of Portugal?At first we were disappointed. Sundials did not seem to be part of the culture in Portugal. But armillary spheres were. They were everywhere. This monumental armillary sphere was in the center of a traffic circle in Albufeira. Why?
3What is an Armillary Sphere? Sundial ?Astronomical instrument?Analogue computer?Navigation tool?Horoscope calculator?Model of the Universe?Symbol of science, technology and the universe?First, what is an armillary sphere? What is its function and why is it so common in Portugal? My search for sundials turned into a great research project.
4Quadrant and RingEquatorial Ring identifies time of equinox when the shadow from the upper ring is totally cast on the lower portion of the ringQuadrant measures noonday altitude of sunHipparchus used the bronze equatorial ring in the Square Hall in Alexandria to determine the equinox and precession about 130 BCSt John’s College, Annapolis
5Greek Armillary Spheres Greek astronomers devised armillary spheres as observational instruments, models of the universe and the basis for navigation and geographyIn his “Almagest”, Ptolemy described the meridian ring (1-12), equatorial ring (3-1), ecliptic observation rings (5-1) and solid celestial sphere (7-4)The history of the armillary sphere.
6Hipparchus Equatorial Ring and Equinox Shadow North PoleHipparchus used the large brass ring set at the angle of the latitude in the great hall in Alexandria. Yes they knew how to use latitude to describe locations on the spherical earth. At the equinox, the shadow of the upper ring is cast on the lower ring. This allowed Hipparchus to determine the exact day of the equinox aand to determine that that day was shifting from the day of the year determined by observing the stars. He discovered and measured precession of the nodes of the ecliptic about 150 BC.LatitudeHipparchus Equatorial Ring and Equinox Shadow
7Ptolemy Meridian Ring and Noon Shadow ZenithPolar AxisPtolemy describes how to build the vertical meridian ring oriented North / South to determine the altitude of the sun at noon and use that to determine the latitude and declination throughout the year.AltitudePtolemy Meridian Ring and Noon Shadow
8Ecliptic Ring = Equatorial Ring + Declination Ecliptic PoleDeclinationNorth PoleThe ecliptic ring showing the plane of the path of the sun moon and planets was the next ring to be added. All these rings were measuring devises, calibrated in degrees and using slots or pegs to sight through. They were often two concentric rings,the one for sighting rotating within the one calibrated for measuring.Ecliptic Ring = Equatorial Ring + Declination
9Ptolemy’s Ecliptic Armillary Ptolemy’s Almagest 5 –1“On the Construction of the Astrolabe”Determine ecliptic coordinates of celestial objectsSet meridian and latitude rings to equatorial poleSight on Inner RingRead ecliptic latitude and longitude ringsSketch from RegiomontanusThey could get pretty fancy. Ptolemy describes this ring. Regiomontanus drew this sketch over 1000 years later based on that description. This allowed determination of coordinates in the ecliptic plane.
10Rings of the Magi ?Armillary used by the ancient astronomers to track the path of the planets, sun and moon and cast horoscopesDid the Magi, Zoroastrian astrologers, use armillary spheres to track the Star of Bethlehem?Heliacal rising of conjunction?Precession to age of Pisces?Were armillary spheres used by the Magi? I like to think they used armillary spheres to track the Star of Bethlehem. I make these armillary sphere Christmas tree ornaments to celebrate that legend.
11Chinese Armillary Spheres Armillary sphere of Guo Shoujing ( ) at the Purple Mountain Observatory at Nanjing.These instruments predate by 350 years similar instruments at the Beijing Ancient Observatory provided by Jesuits (Schall-1666, Verbiest-1673)
12The Dark Ages Vandals sack Rome, Alexandria etc Greek/Roman civilization collapsesWarlords dominate feudal lifeScience moves east with Moslems and HindusTechnology stalled in Europe for over years
13Henry the Navigator Renaissance man 1394-1460 Third son of João & PhillippaSchool of Navigation at Sagres, Cape Vincent, PortugalApplied Ptolemy’s navigation technology: armillary sphere maps and marine astrolabeSponsored “Voyages of Discovery” to Africa, Azores, India, Spice Islands and BrazilWe now get to the connection of armillary spheres with Portugal through Henry the Navigator and his School of Navigation at Sagres.
14Henry and the Discoverers, Belem Henry provided the technology base for the Voyages of Discovery, the trip by Portuguese explorers to Africa, India, the Spice Islands and Brazil in the New World. Note the navigators astrolabe and the armillary sphere, just behind the bible and the sword as the tools of of the explorers.
15Ptolemy's GeographyCelestial sphere defined terrestrial positions on globeEratosthenes, inventor of the armillary sphere, calculated the diameter of the earth from shadow anglesPtolemy's “Geography” gave latitude and longitude for known world from Thule to CeylonThe concepts of a spherical globe and coordinates of Latitude and Longitude were well known to the Greek astronomers. Ptolmey described the world they knew in his other great book “Geography” It described the positions from “Ultima Thule” in Greenland to Ceylon and Indo-China. They were guessing on longitudes as only local time could be measured with sundials. It took a long time to solve the longitude problem.
16Ptolemy's GeographyA Renaissance map based on Ptolemy’s Geography.
17Mariners’ AstrolabeMariners’ astrolabe as used by Portuguese navigators to determine the altitude of the sunReproduction by Tony MossThe other essential tool for navigation, later replaced with the sextant.
18Sacro Bosco’s de Sphaera Mundi John Holywood of Yorkshire, (Joannis de Sacro Bosco) wrote “de Sphaera Mundi” about 1220This text updated Ptolemy and explained the use of armillary spheres in astronomy and navigation“Commentary” by Christoph Clavius 1570Johanis de Sacrobosco, or John Holywood for Yorkshiremen, reintroduced the armillary sphere to the western world with his book “de Sphaera’ about This was based on Ptolemy’s” Almagest”.
19Sagres Compass Rose and Sundial Sagres on the windy south west tip of Europe was the site of Henry’s legendary school of navigation and the point of departure for the “Voyages of Discovery” These artifacts, probably added later, are all that is left behind the fortress wall. Sagres was sacked by that perfidious English privateer, Sir Francis Drake, perhaps as a strategic target but more likely a target of opportunity as the city of Lagos around the corner was too well defended. What we now know of Sagres is based on Drake’s log books.
20Christopher Colombus Portuguese Caravel Christopher Columbus rescued from shipwreck at Sagres in 1479Later he sailed to Madeira, married the daughter of the governor and set up a shipping companySpanish (Ferdinand and Isabella) provided venture capital for his exploration to the new world in 1492 and gained the benefitsDid he learn navigation from the Portuguese at Sagres?Christopher Columbus knew Sagres and the Portuguese navigation technology well.Portuguese Caravel
21Armillary Spheres and Navigation ZenithArmillary Sphere is a model of the UniverseThe earth is round. You cannot sail off the edgeThe position of the sun and stars can tell you where on earth you are, and how to get back to where you startedThe ecliptic ring tells you the declination of the sunThe noon altitude sight and declination determine the latitudeAltitudeDecNorthLatitudeCo-LatitudeHorizonEquatorial RingWhat is the secret of the armillary sphere that is the basis for celestial navigation? It is simple. The sphere determines the declination of the sun. The date is marked around the equatorial and ecliptic rings. For each day, determine the solar declination as the angular distance on a meridian between the ecliptic ring and the equatorial ring. Use an astrolabe to determine the altitude of the sun at its highest point at noon, and calculate your latitude.Ecliptic RingOr ZodiacLat = 90-Alt+ Dec
22Declination Error Analysis Armillary assumes circular orbits vs elliptical. Error?Estimate is reasonable compared to commonly used equationsGreatest error (0.7°) at equinox when rate of change is greatest (0.4°/day)Date of equinox is criticalDoes it work well? It is a reasonable estimate. There is a periodic error because the orbit of the sun is elliptical and not quite circular. Drop the sphere a couple of times and the error will disappear or more likely get worse.
23Wenger UniglobeModern armillary sphere for teaching celestial navigationAdds angle measuring spanner to meridian, great circle and equatorial (time) ringsAdds solution of the navigation triangle to traditional usesThe idea is still useful. Daniel Wenger has reintroduced it, adding an extra arm and building it from modern materials to teach navigation and solve the navigation triangle spherical geometry.
24Armillary Sphere As Astronomical Instrument Ptolemy's brass ringsTycho Brahe’s instruments of 1581Beijing Ancient Observatory of 1670Location at zenithSighting points on meridian ringDetermines celestial coordinates: right ascension and declinationTycho Brahe built this one as an observational instrument based on Ptolemy’s description. It was too diffucult to build, too clumsy to use and too inaccurate to measure the celestial coordinates well.
25Equatorial Armillary Tycho’s great equatorial armillary of 1531 Abandoned as too complex and inaccurateReplaced with giant quadrantHe simplified it to just the equatorial ring but abandoned this as well.
26Armillary Sphere as a Model of the Universe Ptolemy's geocentric modelEarth is a sphere at the center of the universeStars on celestial sphere rotating around the earthCopernicus: Earth and planets rotate around sunSun moon and planets rotate on the ecliptic pathAnomalies as epicyclesKepler: Elliptical orbitsArmillaries had removable centers!The sphere described the geocentric model of the circular spheres of the universe. It did not describe the sun centered elliptical universe of the Copernican Revolution. No problem, it still works well describing the perceived motions of the sun for sundial designers.
27Armillary as a Model of the Universe Demonstrate motions of celestial objectsShow ecliptic path of sun, moon and planetsExplain equinox and precessionExplain solstice and tropicsIt still is useful as a model of the universe to determine those things listed on this slide.
28Armillary as a Computer Translate coordinate systemsHorizon/Zenith: Alt/AzPolar/equatorial: Dec & RAEcliptic: Latitude/LongitudeDetermine position of celestial objectsDetermine declination from dateDetermine latitude from declination and altitudeDetermine rise / set times and azimuthIt is still useful as a computer.
29Armillary as a Symbol Symbol of Science in art Typically a learned man with an armillary, the epitome of knowledgeHere Descartes teaches science to Queen Christina of Sweden“Triumph of Faith” at Jeronimos Monastery, Lisbon shows an armillary sphere as the guide to salvation.It has become an icon of “Science”.
31Portuguese Royal Symbol Portuguese gain control of the spice tradeWealth and power flows to PortugalDom Manuel I adopts the armillary as the Royal symbolManueline architecture uses the Royal Armillary in palaces, churches, monasteries, built with taxes on spicesIt’s importance as the technology for navigation is honoured by its adoption as the Royal Symbol for Portugal This is why armillary spheres are so common in Portugal.Azulejos tile from Sintra Palace
32Portuguese FlagThe armillary sphere:The armillary sphere is a main element in Portuguese heraldry, being incorporated in the modern flag and in a number of historical flags of both Portugal and Brazil. It was an astronomical and navigation instrument made of wood or metal rings ("armilas") interconnected around a central axe to form parallels, meridians and the ecliptic, allowing to calculate one's position on the earth surface by examining the stars. It is usually depicted in heraldry in simplified form, with only one meridian (viewed in a 180 deg. position, as a circle), and only three parallel circles, the equator and the tropics. The ecliptic (sometimes bearing four to six zodiacal signs on it), in descending position on the modern flag's obverse, is usually wider than the other circles. The central axe is also visible, sometimes overlapping the meridian (and in that case we could consider it to be a 0 degrees meridian, viewed as a vertical line...). Anyway, the parallel circles overlap the meridians, and the ecliptic overlaps them all. Older depictions show usually the instrument's "feet", a rotative "stool", as in a modern classroom globes, and sometimes a smaller globe in the center or on the North Pole. The modern version consists of the sphere only, and all the elements are samewhat wider and bearing detailed edges. The width difference between the ecliptic and the other rings is much smaller. António Martins, 28 May 1997
33Manueline Architecture Royal symbols over convent doorway at Estremoz
34Manueline Monasteries Steeple at Jeronimos, BelemCloister tracery at Batalha
35Batalha Cloister Noon Mark But if you look closely you can still find a few sundials in Portugal.
36Typical Portuguese Church Armillary on the steeple of Nossa Senhora da Conceição, Ferragudo
38Portuguese Boom as a High Tech venture Navigation technology conquered the universeVoyages of Discovery gave Portugal the wealth and power of a colonial empireRapid expansion led to huge venture capital requirements for ships, navies, armies, weapons etcProfits diverted to palaces and cathedralsCompetitive spin offs like Columbus and SpainLost technological edge with introduction of the Inquisition and expulsion of the knowledge workersLure and cost of colonies bankrupted Portugal1492 was the year in history that marked the start of the new world order. It was the year that Columbus “discovered” America and the year the Catholic rulers expelled the Jews and Moslems from Spain and Portugal.
39Armillary Spheres and Sundials Waugh armillary at Mystic, CTArmillary spheres lead to sundial designsEquatorialPolarAnalemmaticHorizontal / VerticalWenger GlobeBack on topic, armillary sphere are the basis for almost all types and styles of sundials. Everything I need to know about sundial design, I learned from armillary spheres.
40Armillary Spheres and Equatorial Sundials Schmoyer Dial by Tony Moss for Mike ShawGnomon is polar axisEQT correction in gnomonHour scale on equatorial ringLinear scale 15°/hourRing opened to avoid equinox shadows
41Roger’s Equatorial Stainless steel (316L) 12” pipe sections Hand crafted with hack saw and filesPort Elgin, OntLat N 45:28:00Long W 81:24:30
42Armillary Sphere and Polar Sundials Flatten the equatorial ring in the plane of the polar axisDistance = r Tan ttr
43Armillary Spheres and Planar Sundials The blue ring represents the plane of the sundial in relation to the celestial sphere. Look at the hour lines from the center to the ring intersecting the meridian rings. Rotate the ring or the sphere to get the hour lines for any planar sundial for any location.Luke Coletti gcstudio.com
44Armillary and Analemmatic Sundial Project equatorial ring on plane for ellipseProject gnomon on plane for zodiacDeclination on gnomon determines zodiac positionsImage by Frans MaesProject the armillary sphere equatorial ring and the gnomon onto a plane to design an analemmatic sundial. The concept is that simple.
45Armillary Sphere and Analemmatic Sundials Equatorial ring projects as an ellipseShape depends on latitude- DLGnomon projects as Zodiacon north south axis forvarious solar declinationsThis is an engineering type drawing of two plane views showing the projection of the ring and gnomon to the ellipse and zodiac.ZodiacN
46Wenger Sundial Glass sphere inscribed with armillary rings Hour meridiansHorizonTropics and analemmasLocation at ZenithShadow on center point gives timeDesign by Daniel WengerAnother great and novel sundial design by Daniel Wenger based on the armillary sphere.
47Modern Armillary Spheres Prime market is for symbolic ornaments like garden variety sundialsLots of junk is offered for saleRings should represent the universeEquatorial, ecliptic, meridian, horizon etcEcliptic ring should rotateMust be set for latitudeShould have scales for hours, degrees and dateThere is lots of junk out there!
48Classic Armillary Sphere Meridian ring engraved for declination and latitudeEquatorial ringRotating ecliptic ring with engraved zodiacTropic and polar circlesBut also some proper instruments.Horizon ring engraved for degrees and dateColure rings through poleSource: Classical Science