{"id":2283,"date":"2021-04-27T10:16:25","date_gmt":"2021-04-27T10:16:25","guid":{"rendered":"http:\/\/meumon.synology.me\/museu\/?p=2283"},"modified":"2023-08-04T11:52:42","modified_gmt":"2023-08-04T11:52:42","slug":"lastrolabi","status":"publish","type":"post","link":"http:\/\/meumon.synology.me\/museu\/lastrolabi\/","title":{"rendered":"L’astrolabi"},"content":{"rendered":"

\u2191\u00a0\u00a0 El firmament<\/a><\/p>\n

\n

viquipedia<\/a><\/p>\n

\u00c9s un instrument que combina un planisferi amb un inclin\u00f2metre per mesurar l’al\u00e7ada d’un objecte sobre l’horitz\u00f3.\u00a0 El van fer servir els grecs i a l’edat mitjana els \u00e0rabs e van perfeccionar.<\/p>\n

A In the sky<\/a> se’n pot decarregar un model per imprimir per la latitud de 40\u00ba. A Astrolabeproject<\/a> un programa per adaptar-lo a qualsevol latitud.<\/p>\n

Funcionament (basat en el primer model)<\/p>\n

(1) 1a<\/strong> La part de darrera de la “mare” t\u00e9 una alidada per mesurar l’al\u00e7ada d’una estrella [ coordenades estelars ascensi\u00f3 recta (longitud) o declinaci\u00f3 \/ coordenades de l’horitz\u00f3, altitude i azimuth], i situar el sol a la seva constel\u00b7laci\u00f3 sobre el cercle m\u00e9s exterior. 1b<\/strong> Les constel\u00b7lacions del zod\u00edac al llarg de l’ecl\u00edptica, dividides en 30\u00ba. 1c<\/strong> el calendari de 1394 quan Chaucer va escriure el tractat sobre astrolabis. 1d<\/strong> el calendari actual, despla\u00e7at 9 dies.\u00a0 1e<\/strong> Calendari lit\u00fargic amb les dates d’alguns sants (a number of significant Christian saints, 1f<\/strong> Umbra i recta trobar la ra\u00f3 entre l’al\u00e7ada i la dist\u00e0ncia a partir de l’angle d’elevaci\u00f3. Indica x\/12, \u00e9s a dir, amb 45\u00ba marca 12 (12\/12), amb 15\u00ba \u00e9s 3\/12.<\/p>\n

(2) Frontal 2a<\/strong> el cercle de les hores + \u00e9s migdia i la M mitja nit, la resta representada per lletres. 2b<\/strong> la rete t\u00e9 una projecci\u00f3 horitzontal de les estrelles, amb la polar al centre, i marcats hi ha el tr\u00f2pic de c\u00e0ncer (23.5 per sobre), l’equador i el tr\u00f2pic de capricorni (23.5 per sota l’equador).[coincidint amb aix\u00f2] hi ha l’ascensi\u00f3 recta. la rgela indica la declinaci\u00f3 d’una estrella respecte de l’equador [ex, S\u00edrius est\u00e0 a 6.8 ar i -18\u00ba de declinaci\u00f3]. If you are already familiar with the constellations, you may notice the surprising fact that the rete depicts all of the constellations back-to-front. Objects that appear to the left of Orion in the sky, appear to the right of it on the rete. Why did I make such a mistake?This is a historically authentic reproduction of the retes on the vast majority of medieval astrolabes, including the one described by Chaucer.\u00a0 2c<\/strong> To find the position of the Sun on any given day, the scale on the reverse side of the mother is used. For example, on 1st June, the scales on the reverse side tell us that the Sun has moved approximately 10\u00b0 through the constellation of Gemini. Turning back to the front of the astrolabe, we see on the rete that the point 10\u00b0 through Gemini is a little to the north of Aldebaran. 2d<\/strong> The climate sits directly behind the rete, and shows a cobweb-like grid of lines that represent the visible portion of the sky. The criss-crossing lines are lines of constant altitude \u2013 called almucantars \u2013 and lines of constant azimuth \u2013 called azimuths \u2013 and they are used to determine the approximate alt\/az coordinates of stars. The thick line at the outermost edge of the cobweb pattern shows the horizon of the visible sky. Just as on a modern planisphere, the rotation of the sky through the night is reproduced by rotating the star chart \u2013 in this case, the rete. As the rete is rotated clockwise, stars are seen to rise in the east and set in the west.As with a planisphere, the star chart must be brought into the correct rotation to represent a particular time and date before it can be used. On a planisphere, this is usually done by matching the desired time on a rotating scale to the desired date on a static scale marked around the edge of the planisphere. On an astrolabe, however, no such scales are provided. Alignment is usually achieved by measuring the altitude of a reference object \u2013 either the Sun or a star \u2013 using the alidade and then rotating the rete until its projection lies on the appropriate almucantar. [ si conec al meu horitz\u00f3, puc tenir una idea prou bona de l’azimuth, i l’altitud \u00e9s el que m’ha donat la mesura amb l’alidada, aix\u00ed puc girar la rete a la posici\u00f3 correcta i veure on estan les altres estrelles]. 2e<\/strong> les hores desiguals (dividir la nit en 12, el dia en 12 que varia segons som a l’hivern o l’estiu) i les hores iguals.<\/p>\n

\n

descarregable<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

\u2191\u00a0\u00a0 El firmament viquipedia \u00c9s un instrument que combina un planisferi amb un inclin\u00f2metre per mesurar l’al\u00e7ada d’un objecte sobre l’horitz\u00f3.\u00a0 El van fer servir els grecs i a l’edat mitjana els \u00e0rabs e van perfeccionar. A In the sky se’n pot decarregar un model per imprimir per la latitud de 40\u00ba. A Astrolabeproject un … <\/p>\n

Continue reading “L’astrolabi”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[606],"tags":[333],"anotacio":[],"civilitzacio":[],"spec":[],"aspecies":[],"Tema poesia":[],"_links":{"self":[{"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/posts\/2283"}],"collection":[{"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/comments?post=2283"}],"version-history":[{"count":0,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/posts\/2283\/revisions"}],"wp:attachment":[{"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/media?parent=2283"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/categories?post=2283"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/tags?post=2283"},{"taxonomy":"anotacio","embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/anotacio?post=2283"},{"taxonomy":"civilitzacio","embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/civilitzacio?post=2283"},{"taxonomy":"spec","embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/spec?post=2283"},{"taxonomy":"aspecies","embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/aspecies?post=2283"},{"taxonomy":"Tema poesia","embeddable":true,"href":"http:\/\/meumon.synology.me\/museu\/wp-json\/wp\/v2\/Tema poesia?post=2283"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}