{"id":145,"date":"2023-10-29T14:10:51","date_gmt":"2023-10-29T14:10:51","guid":{"rendered":"http:\/\/matastro.pt\/astro\/?page_id=145"},"modified":"2023-10-29T14:13:14","modified_gmt":"2023-10-29T14:13:14","slug":"o-analema-solar","status":"publish","type":"page","link":"http:\/\/matastro.pt\/astro\/o-analema-solar\/","title":{"rendered":"O analema solar"},"content":{"rendered":"\n<p>O Analema solar traduz o efeito da varia\u00e7\u00e3o da posi\u00e7\u00e3o do Sol ao longo de um ano (resultante da excentricidade da \u00f3rbita terrestre e da inclina\u00e7\u00e3o do eixo de rota\u00e7\u00e3o relativamente \u00e0 ecl\u00edptica). Numa an\u00e1lise simples o analema representa o tempo de atraso ou de adiantamento do Sol em rela\u00e7\u00e3o \u00e0 sua passagem meridana: ou seja traduz a diferen\u00e7a do comprimento dos dias solares e portanto, a chamada Equa\u00e7\u00e3o do Tempo que estabelece a diferen\u00e7a entre o tempo solar verdadeiro e o tempo solar m\u00e9dio.<\/p>\n\n\n\n<p>Analisando a figura do Analema notar-se-\u00e1 que a parte da curva correspondente ao Outono e Inverno \u00e9 um pouco mais larga que a parte correspondente \u00e0 Primavera e ao Ver\u00e3o. Isto verifica-se porque em Janeiro a Terra est\u00e1 mais pr\u00f3xima do Sol e, por isso, a sua velocidade angular orbital ser\u00e1 tamb\u00e9m maior como nos diz a 2.\u00aa&nbsp; Lei de Kepler.<\/p>\n\n\n\n<div class=\"wp-block-media-text is-stacked-on-mobile\"><figure class=\"wp-block-media-text__media\"><img loading=\"lazy\" decoding=\"async\" width=\"750\" height=\"582\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/analemme-dicicco.jpg\" alt=\"\" class=\"wp-image-146 size-full\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/analemme-dicicco.jpg 750w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/analemme-dicicco-300x233.jpg 300w\" sizes=\"auto, (max-width: 750px) 100vw, 750px\" \/><\/figure><div class=\"wp-block-media-text__content\">\n<p><em>A c\u00e9lebre fotografia de Dennis di Cicco representando as sucessivas posi\u00e7\u00f5es do Sol num mesmo local \u00e0 mesma hora durante um ano.<\/em><\/p>\n<\/div><\/div>\n\n\n\n<p>A sequ\u00eancia seguinte de imagens \u00e9 demonstrativa da diferen\u00e7a entre uma \u00f3rbita circular com velocidade constante e a \u00f3rbita el\u00edptica da Terra.<\/p>\n\n\n\n<figure class=\"wp-block-gallery has-nested-images columns-default is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"152\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a1.png\" alt=\"\" class=\"wp-image-152\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a1.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a1-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"153\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a2.png\" alt=\"\" class=\"wp-image-153\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a2.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a2-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"150\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a3.png\" alt=\"\" class=\"wp-image-150\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a3.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a3-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"149\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a4.png\" alt=\"\" class=\"wp-image-149\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a4.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a4-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"154\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a5.png\" alt=\"\" class=\"wp-image-154\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a5.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a5-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"151\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a6.png\" alt=\"\" class=\"wp-image-151\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a6.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a6-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"160\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a7.png\" alt=\"\" class=\"wp-image-160\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a7.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a7-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"156\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a8.png\" alt=\"\" class=\"wp-image-156\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a8.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a8-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"159\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a9.png\" alt=\"\" class=\"wp-image-159\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a9.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a9-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"158\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a10.png\" alt=\"\" class=\"wp-image-158\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a10.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a10-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"155\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a11.png\" alt=\"\" class=\"wp-image-155\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a11.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a11-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"312\" height=\"301\" data-id=\"157\" src=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a12.png\" alt=\"\" class=\"wp-image-157\" srcset=\"http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a12.png 312w, http:\/\/matastro.pt\/astro\/wp-content\/uploads\/2023\/10\/a12-300x289.png 300w\" sizes=\"auto, (max-width: 312px) 100vw, 312px\" \/><\/figure>\n<\/figure>\n\n\n\n<p>O analema \u00e9 invariante com a longitude, varia apenas com a latitude. Obt\u00e9m-se um &#8220;8&#8221; exatamente na vertical no p\u00f3lo e vai rodando at\u00e9 ficar um &#8220;8&#8221; &#8220;deitado&#8221; no equador.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>O Analema solar traduz o efeito da varia\u00e7\u00e3o da posi\u00e7\u00e3o do Sol ao longo de um ano (resultante da excentricidade da \u00f3rbita terrestre e da inclina\u00e7\u00e3o do eixo de rota\u00e7\u00e3o relativamente \u00e0 ecl\u00edptica). Numa an\u00e1lise simples o analema representa o tempo de atraso ou de adiantamento do Sol em rela\u00e7\u00e3o \u00e0 sua passagem meridana: ou [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-145","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/matastro.pt\/astro\/wp-json\/wp\/v2\/pages\/145","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/matastro.pt\/astro\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/matastro.pt\/astro\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/matastro.pt\/astro\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/matastro.pt\/astro\/wp-json\/wp\/v2\/comments?post=145"}],"version-history":[{"count":2,"href":"http:\/\/matastro.pt\/astro\/wp-json\/wp\/v2\/pages\/145\/revisions"}],"predecessor-version":[{"id":161,"href":"http:\/\/matastro.pt\/astro\/wp-json\/wp\/v2\/pages\/145\/revisions\/161"}],"wp:attachment":[{"href":"http:\/\/matastro.pt\/astro\/wp-json\/wp\/v2\/media?parent=145"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}