{"id":29089,"date":"2026-10-23T08:35:31","date_gmt":"2026-10-23T08:35:31","guid":{"rendered":"https:\/\/www.worldclock.com\/calcul-temps-sideral\/"},"modified":"2026-10-23T08:35:31","modified_gmt":"2026-10-23T08:35:31","slug":"calcul-temps-sideral","status":"publish","type":"page","link":"https:\/\/www.worldclock.com\/fr\/calcul-temps-sideral\/","title":{"rendered":"Calculateur de temps sid\u00e9ral et de jour julien"},"content":{"rendered":"<div class=\"wc wc-tool-page wc-tool-page--sidereal\"><header class=\"wc-thero\"><div class=\"wc-thero__text\"><nav class=\"wc-crumbs\" aria-label=\"Breadcrumb\"><ol><li><a href=\"https:\/\/www.worldclock.com\/fr\/\">Horloge mondiale<\/a><\/li><li><a href=\"https:\/\/www.worldclock.com\/fr\/outils\/\">Outils horaires<\/a><\/li><li><span aria-current=\"page\">Calculateur de temps sid\u00e9ral et de jour julien<\/span><\/li><\/ol><\/nav><p class=\"wc-eyebrow\"><span aria-hidden=\"true\">\ud83c\udf0c<\/span> Outil gratuit<\/p><h1 class=\"wc-thero__title\">Calculateur de temps sid\u00e9ral et de jour julien<\/h1><p class=\"wc-thero__lead\">Temps sid\u00e9ral local, temps sid\u00e9ral de Greenwich, jour julien et jour julien modifi\u00e9 en direct pour n\u2019importe quel lieu et n\u2019importe quelle heure.<\/p><\/div><\/header><div class=\"wc-tool\"><div class=\"wc-sid\" data-wc-tool=\"sidereal\" data-default=\"{&quot;n&quot;:&quot;Greenwich&quot;,&quot;t&quot;:&quot;Europe\\\/London&quot;,&quot;f&quot;:&quot;gb&quot;,&quot;a&quot;:51.4769,&quot;o&quot;:-0.0005}\"><div class=\"wc-tbar\"><div class=\"wc-field wc-field--grow\"><span>Lieu<\/span><div class=\"wc-search wc-search--tool\" data-wc-search data-mode=\"add\"><input type=\"search\" placeholder=\"Rechercher une ville\u2026\" aria-label=\"Rechercher une ville\u2026\" autocomplete=\"off\"><ul class=\"wc-search__results\" hidden><\/ul><\/div><\/div><label class=\"wc-field\"><span>Longitude \u00b0<\/span><input type=\"number\" step=\"0.0001\" min=\"-180\" max=\"180\" data-lng><\/label><button type=\"button\" class=\"wc-btn wc-btn--ghost\" data-geo>\ud83d\udccd Utiliser ma position<\/button><\/div><div class=\"wc-sunc__place\" data-place><\/div><div class=\"wc-sunc__cards\" data-cards><\/div><div class=\"wc-panel\" style=\"margin-top:16px\"><h2>Convertir une date<\/h2><label class=\"wc-field\"><span>Date et heure (UTC)<\/span><input type=\"datetime-local\" step=\"1\" data-dt><\/label><dl class=\"wc-unix__out\" data-out><\/dl><\/div><\/div><\/div><section class=\"wc-section wc-tool-info\"><div class=\"wc-prose\"><h2>Qu\u2019est-ce que le temps sid\u00e9ral ?<\/h2><p>Le temps sid\u00e9ral mesure la rotation de la Terre par rapport aux \u00e9toiles lointaines plut\u00f4t qu\u2019au soleil. Un jour sid\u00e9ral dure environ <strong>23 heures 56 minutes 4 secondes<\/strong> \u2013 pr\u00e8s de quatre minutes de moins qu\u2019un jour solaire \u2013 si bien que les \u00e9toiles se l\u00e8vent quatre minutes plus t\u00f4t chaque nuit. Les astronomes utilisent le <strong>temps sid\u00e9ral local (TSL)<\/strong> pour pointer leurs t\u00e9lescopes : une \u00e9toile est au plus haut dans le ciel lorsque le TSL est \u00e9gal \u00e0 son ascension droite.<\/p><p>Le <strong>jour julien<\/strong> est un d\u00e9compte continu des jours depuis le 1er janvier 4713 av. J.-C. \u00e0 midi UTC, utilis\u00e9 en astronomie pour \u00e9viter les complications calendaires. Le <strong>jour julien modifi\u00e9<\/strong> (MJD) est \u00e9gal \u00e0 JD \u2212 2 400 000,5 et commence \u00e0 minuit.<\/p><\/div><\/section><section class=\"wc-section wc-faq\"><h2>Questions fr\u00e9quentes<\/h2><details><summary>Comment calculer le temps sid\u00e9ral local ?<\/summary><p>Calculez le temps sid\u00e9ral moyen de Greenwich \u00e0 partir du jour julien, puis ajoutez votre longitude en heures (longitude \u00f7 15, positive vers l\u2019est). Le calculateur ci-dessus le fait en direct pour n\u2019importe quel lieu.<\/p><\/details><\/section><section class=\"wc-section wc-tools-grid\"><div class=\"wc-section__head\"><h2>Plus d\u2019outils horaires gratuits<\/h2><a href=\"https:\/\/www.worldclock.com\/fr\/outils\/\">Tous les outils \u2192<\/a><\/div><div class=\"wc-toolcards\"><a class=\"wc-toolcard wc-toolcard--sun\" href=\"https:\/\/www.worldclock.com\/fr\/lever-coucher-soleil\/\"><span class=\"wc-toolcard__icon\" aria-hidden=\"true\">\ud83c\udf05<\/span><span class=\"wc-toolcard__name\">Calculateur de lever et coucher du soleil<\/span><span class=\"wc-toolcard__desc\">Lever, coucher du soleil et heure dor\u00e9e.<\/span><\/a><a class=\"wc-toolcard wc-toolcard--golden\" href=\"https:\/\/www.worldclock.com\/fr\/calcul-heure-doree\/\"><span class=\"wc-toolcard__icon\" aria-hidden=\"true\">\ud83d\udcf8<\/span><span class=\"wc-toolcard__name\">Calculateur d\u2019heure dor\u00e9e<\/span><span class=\"wc-toolcard__desc\">La meilleure lumi\u00e8re pour vos photos.<\/span><\/a><a class=\"wc-toolcard wc-toolcard--moon\" href=\"https:\/\/www.worldclock.com\/fr\/phase-de-la-lune\/\"><span class=\"wc-toolcard__icon\" aria-hidden=\"true\">\ud83c\udf15<\/span><span class=\"wc-toolcard__name\">Phase de la lune aujourd\u2019hui<\/span><span class=\"wc-toolcard__desc\">La lune ce soir et calendrier lunaire.<\/span><\/a><a class=\"wc-toolcard wc-toolcard--fullmoon\" href=\"https:\/\/www.worldclock.com\/fr\/calendrier-pleine-lune\/\"><span class=\"wc-toolcard__icon\" aria-hidden=\"true\">\ud83c\udf1d<\/span><span class=\"wc-toolcard__name\">Calendrier des pleines lunes<\/span><span class=\"wc-toolcard__desc\">Dates et noms des pleines lunes.<\/span><\/a><a class=\"wc-toolcard wc-toolcard--moonrise\" href=\"https:\/\/www.worldclock.com\/fr\/lever-coucher-lune\/\"><span class=\"wc-toolcard__icon\" aria-hidden=\"true\">\ud83c\udf19<\/span><span class=\"wc-toolcard__name\">Heures de lever et coucher de la lune<\/span><span class=\"wc-toolcard__desc\">Quand la lune se l\u00e8ve et se couche.<\/span><\/a><a class=\"wc-toolcard wc-toolcard--birthmoon\" href=\"https:\/\/www.worldclock.com\/fr\/phase-lune-anniversaire\/\"><span class=\"wc-toolcard__icon\" aria-hidden=\"true\">\ud83c\udf82<\/span><span class=\"wc-toolcard__name\">La lune le jour de votre naissance<\/span><span class=\"wc-toolcard__desc\">La lune \u00e0 n\u2019importe quelle date.<\/span><\/a><a class=\"wc-toolcard wc-toolcard--astro\" href=\"https:\/\/www.worldclock.com\/fr\/calendrier-astronomique\/\"><span class=\"wc-toolcard__icon\" aria-hidden=\"true\">\ud83d\udd2d<\/span><span class=\"wc-toolcard__name\">Calendrier astronomique<\/span><span class=\"wc-toolcard__desc\">\u00c9clipses, \u00e9toiles filantes et ph\u00e9nom\u00e8nes c\u00e9lestes.<\/span><\/a><a class=\"wc-toolcard wc-toolcard--converter\" href=\"https:\/\/www.worldclock.com\/fr\/convertisseur-fuseaux-horaires\/\"><span class=\"wc-toolcard__icon\" aria-hidden=\"true\">\ud83d\udd01<\/span><span class=\"wc-toolcard__name\">Convertisseur de fuseaux horaires<\/span><span class=\"wc-toolcard__desc\">Convertir une heure entre n\u2019importe quelles villes.<\/span><\/a><\/div><\/section><\/div>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_kad_blocks_custom_css":"","_kad_blocks_head_custom_js":"","_kad_blocks_body_custom_js":"","_kad_blocks_footer_custom_js":"","_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","footnotes":"","bs_cache_bypass_cache":0,"bs_cache_related_page":0},"class_list":["post-29089","page","type-page","status-publish","hentry"],"acf":[],"taxonomy_info":[],"featured_image_src_large":false,"author_info":{"display_name":"clocker","author_link":"https:\/\/www.worldclock.com\/fr\/author\/clocker\/"},"comment_info":"","_links":{"self":[{"href":"https:\/\/www.worldclock.com\/fr\/wp-json\/wp\/v2\/pages\/29089","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.worldclock.com\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.worldclock.com\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.worldclock.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.worldclock.com\/fr\/wp-json\/wp\/v2\/comments?post=29089"}],"version-history":[{"count":0,"href":"https:\/\/www.worldclock.com\/fr\/wp-json\/wp\/v2\/pages\/29089\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.worldclock.com\/fr\/wp-json\/wp\/v2\/media?parent=29089"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}