{"id":197,"date":"2021-12-02T12:43:24","date_gmt":"2021-12-02T11:43:24","guid":{"rendered":"https:\/\/kids.esa.int\/the_universe\/"},"modified":"2026-10-08T00:25:22","modified_gmt":"2026-10-07T22:25:22","slug":"the_universe","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fr\/the_universe\/","title":{"rendered":"L\u2019Univers"},"content":{"rendered":"
\n

L\u2019univers, c\u2019est tout ce que l\u2019on peut toucher, d\u00e9tecter, sentir, mesurer ou d\u00e9celer. Il comprend les \u00eatres et organismes vivants, les plan\u00e8tes, les \u00e9toiles, les galaxies, les nuages de poussi\u00e8res, la lumi\u00e8re et m\u00eame le temps. Avant la naissance de l\u2019univers, les notions de temps, d\u2019espace et de mati\u00e8re n\u2019existaient pas.<\/p>\n<\/div>\n

L\u2019univers recense des milliards de galaxies, chacune contenant des millions ou des milliards d\u2019\u00e9toiles. L\u2019espace entre les \u00e9toiles et les galaxies est essentiellement vide. Cependant, m\u00eame les lieux tr\u00e8s \u00e9loign\u00e9s des \u00e9toiles et des plan\u00e8tes contiennent des particules \u00e9parses de poussi\u00e8res ou quelques atomes d\u2019hydrog\u00e8ne par centim\u00e8tre cube. L\u2019espace est \u00e9galement empli de rayonnement (par ex. la lumi\u00e8re et la chaleur), de champs magn\u00e9tiques et de particules d\u2019\u00e9nergie \u00e9lev\u00e9e (comme les rayons cosmiques).<\/p>\n

L\u2019univers est incroyablement vaste. Il faudrait \u00e0 un chasseur \u00e0 r\u00e9action moderne plus d\u2019un million d\u2019ann\u00e9es pour atteindre l\u2019\u00e9toile la plus proche du Soleil. \u00c0 la vitesse de la lumi\u00e8re (300 000 km par seconde), il faudrait 100 000 ans pour traverser rien que notre Voie lact\u00e9e.<\/p>\n

Personne ne conna\u00eet la taille exacte de l\u2019univers, car nous ne pouvons en voir le bout \u2013 s\u2019il tant est qu\u2019il y en ait un. Tout ce que nous savons, c\u2019est que l\u2019univers visible s\u2019\u00e9tend sur une distance d\u2019au moins 93 milliards d\u2019ann\u00e9es lumi\u00e8re. (Une ann\u00e9e lumi\u00e8re est la distance que parcourt la lumi\u00e8re en une ann\u00e9e \u2013 soit pr\u00e8s de 9 000 milliards de kilom\u00e8tres.)<\/p>\n

L\u2019univers n\u2019a pas toujours eu la m\u00eame taille. Les scientifiques pensent que l\u2019univers est n\u00e9 lors d\u2019un Big Bang qui a eu lieu il y a 14 milliards d\u2019ann\u00e9es. Depuis, l\u2019univers n\u2019a cess\u00e9 de grandir \u00e0 tr\u00e8s grande vitesse. Ainsi, l\u2019espace que nous voyons maintenant est des milliards de fois plus \u00e9tendu qu\u2019au d\u00e9but de l\u2019univers. Les galaxies s\u2019\u00e9loignent les unes des autres au fur et \u00e0 mesure que l\u2019espace entre elles se d\u00e9ploie.<\/p>","protected":false},"excerpt":{"rendered":"

The Universe is everything we can touch, feel, sense, measure or detect. It includes living things, planets, stars, galaxies, dust clouds, light, and even time. Before the birth of the […]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"esa_banner_image":"https:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2010\/06\/the_massive_compact_star_cluster_in_ngc_3603_and_its_surroundings2\/18245403-2-eng-GB\/The_massive_compact_star_cluster_in_NGC_3603_and_its_surroundings.jpg","esa_banner_description":"","esa_banner_credit":"NASA\/ESA\/Hubble Heritage (STScI\/AURA)-ESA\/Hubble Collaboration","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2010\/06\/The_massive_compact_star_cluster_in_NGC_3603_and_its_surroundings2","esa_external_url":"","esa_external_new_window":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":true},"categories":[10,11,19],"tags":[2],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-197","post","type-post","status-publish","format-standard","hentry","category-learn","category-our-universe","category-story-of-the-universe","tag-background-article"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/posts\/197","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/comments?post=197"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/posts\/197\/revisions"}],"predecessor-version":[{"id":1340,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/posts\/197\/revisions\/1340"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/media?parent=197"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/categories?post=197"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/tags?post=197"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/panel?post=197"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/language?post=197"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/age?post=197"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/duration?post=197"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/resource_type?post=197"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/audience?post=197"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/wf_post_folders?post=197"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}