{"id":3399,"date":"2026-04-03T18:15:33","date_gmt":"2026-04-03T16:15:33","guid":{"rendered":"https:\/\/www-new.ias.u-psud.fr\/?p=3399"},"modified":"2026-09-25T12:08:23","modified_gmt":"2026-09-25T10:08:23","slug":"majis-detecte-lactivite-de-lobjet-interstellaire-3i-atlas","status":"publish","type":"post","link":"https:\/\/www.ias.u-psud.fr\/index.php\/2026\/04\/03\/majis-detecte-lactivite-de-lobjet-interstellaire-3i-atlas\/","title":{"rendered":"MAJIS d\u00e9tecte l\u2019activit\u00e9 de l\u2019objet interstellaire 3I\/ATLAS"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"3399\" class=\"elementor elementor-3399\" data-elementor-post-type=\"post\">\n\t\t\t\t<div class=\"elementor-element elementor-element-365d0f3 e-flex e-con-boxed e-con e-parent\" data-id=\"365d0f3\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-84ab3f5 elementor-widget elementor-widget-theme-post-featured-image elementor-widget-image\" data-id=\"84ab3f5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"theme-post-featured-image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" width=\"1024\" height=\"996\" src=\"https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1-1024x996.png\" class=\"attachment-large size-large wp-image-3401\" alt=\"\" srcset=\"https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1-1024x996.png 1024w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1-300x292.png 300w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1-768x747.png 768w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1.png 1200w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f4f600f e-flex e-con-boxed e-con e-parent\" data-id=\"f4f600f\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-63f7b05 elementor-widget elementor-widget-theme-post-title elementor-page-title elementor-widget-heading\" data-id=\"63f7b05\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"theme-post-title.default\">\n\t\t\t\t\t<h1 class=\"elementor-heading-title elementor-size-default\">MAJIS d\u00e9tecte l\u2019activit\u00e9 de l\u2019objet interstellaire 3I\/ATLAS<\/h1>\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-9b7c05e e-con e-atomic-element e-flexbox-base e-9b7c05e-607ee4c \" data-id=\"9b7c05e\" data-element_type=\"e-flexbox\" data-e-type=\"e-flexbox\" data-interaction-id=\"9b7c05e\">\n    \t\t<div class=\"elementor-element elementor-element-d72e17c elementor-widget elementor-widget-text-editor\" data-id=\"d72e17c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>En novembre 2025, la mission Juice de l\u2019ESA a observ\u00e9 la com\u00e8te interstellaire 3I\/ATLAS, un visiteur rare venu d\u2019un autre syst\u00e8me stellaire.\u00a0\u00c0 cette occasion, l\u2019instrument <a title=\"https:\/\/www.ias.universite-paris-saclay.fr\/fr\/content\/juicemajis\" href=\"https:\/\/www.ias.u-psud.fr\/index.php\/2026\/07\/31\/majis\/\" target=\"_blank\" rel=\"noopener\"><u>MAJIS<\/u><\/a> a mis en \u00e9vidence des \u00e9missions de vapeur d\u2019eau et de dioxyde de carbone, r\u00e9v\u00e9lant une activit\u00e9 com\u00e9taire intense peu apr\u00e8s son passage au plus pr\u00e8s du Soleil.\u00a0Ces observations traduisent la sublimation de glaces enfouies sous la surface, lib\u00e9r\u00e9es sous l\u2019effet du r\u00e9chauffement solaire. Le d\u00e9gazage, estim\u00e9 \u00e0 environ 2 tonnes par seconde, t\u00e9moigne d\u2019un processus particuli\u00e8rement actif.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\n<\/div>\n\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-5612ae1 e-flex e-con-boxed e-con e-parent\" data-id=\"5612ae1\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t<div class=\"elementor-element elementor-element-8d2c731 e-con e-atomic-element e-flexbox-base e-8d2c731-bc6f834 \" data-id=\"8d2c731\" data-element_type=\"e-flexbox\" data-e-type=\"e-flexbox\" data-interaction-id=\"8d2c731\">\n    \t\t<div class=\"elementor-element elementor-element-10d0162 elementor-widget elementor-widget-text-editor\" data-id=\"10d0162\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Malgr\u00e9 des conditions d\u2019observation exigeantes (faible signal et contraintes thermiques) MAJIS a \u00e9galement d\u00e9tect\u00e9 des \u00e9missions plus faibles \u00e0 la mi-novembre. Les donn\u00e9es, re\u00e7ues seulement fin f\u00e9vrier 2026 en raison de la configuration orbitale et de l\u2019attitude du satellite ne permettant pas d\u2019orienter ses antennes de t\u00e9l\u00e9communication vers la Terre, ont donc permis de fournir des donn\u00e9es uniques de cet objet exceptionnel.<\/p><p>D\u00e9couvert en juillet 2025, 3I\/ATLAS est seulement le troisi\u00e8me objet interstellaire identifi\u00e9 traversant notre Syst\u00e8me solaire. Ces r\u00e9sultats coupl\u00e9s aux observations JWST ou des grands t\u00e9lescopes sol ouvrent une fen\u00eatre unique sur la composition de mat\u00e9riaux form\u00e9s autour d\u2019une autre \u00e9toile il y a des milliards d\u2019ann\u00e9es.<\/p><p>Ils illustrent \u00e9galement la capacit\u00e9 de MAJIS \u00e0 d\u00e9tecter des signaux extr\u00eamement faibles.Une performance prometteuse pour les futures observations de signaux faibles tels que les exosph\u00e8res des lunes glac\u00e9es et des anneaux de Jupiter.<\/p><p>L\u2019instrument MAJIS est un spectrom\u00e8tre imageur visible-infrarouge, qui a notamment pour mission de caract\u00e9riser les surfaces et les exosph\u00e8res des lunes de Jupiter ainsi que l\u2019atmosph\u00e8re de Jupiter. L\u2019Institut d\u2019astrophysique spatiale est responsable scientifique et technique de l\u2019instrument.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\n<\/div>\n\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-387dca1 e-con e-atomic-element e-flexbox-base e-356ef4e \" data-id=\"387dca1\" data-element_type=\"e-flexbox\" data-e-type=\"e-flexbox\" data-interaction-id=\"387dca1\">\n    \t\t<div class=\"elementor-element elementor-element-5a5d233 elementor-widget elementor-widget-image\" data-id=\"5a5d233\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"300\" height=\"292\" src=\"https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1-300x292.png\" class=\"attachment-medium size-medium wp-image-3401\" alt=\"\" srcset=\"https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1-300x292.png 300w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1-1024x996.png 1024w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1-768x747.png 768w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig1.png 1200w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\n<\/div>\n<div class=\"elementor-element elementor-element-971042f e-con e-atomic-element e-flexbox-base e-971042f-752270f \" data-id=\"971042f\" data-element_type=\"e-flexbox\" data-e-type=\"e-flexbox\" data-interaction-id=\"971042f\">\n    \t\t<div class=\"elementor-element elementor-element-8d56b97 elementor-widget elementor-widget-text-editor\" data-id=\"8d56b97\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Image 1 : Observation MAJIS de la com\u00e8te superpos\u00e9e \u00e0 l\u2019image NavCam\/Juice le 02\/11\/2026<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\n<\/div>\n<div class=\"elementor-element elementor-element-5fe98c8 e-con e-atomic-element e-flexbox-base e-5fe98c8-0afa60d \" data-id=\"5fe98c8\" data-element_type=\"e-flexbox\" data-e-type=\"e-flexbox\" data-interaction-id=\"5fe98c8\">\n    \t\t<div class=\"elementor-element elementor-element-2bb139d elementor-widget elementor-widget-image\" data-id=\"2bb139d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"300\" height=\"250\" src=\"https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig2-300x250.png\" class=\"attachment-medium size-medium wp-image-3402\" alt=\"\" srcset=\"https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig2-300x250.png 300w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig2-1024x852.png 1024w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig2-768x639.png 768w, https:\/\/www.ias.u-psud.fr\/wp-content\/uploads\/2026\/04\/202604-majis-fig2.png 1200w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\n<\/div>\n<div class=\"elementor-element elementor-element-00551c2 e-con e-atomic-element e-flexbox-base e-96599f0 \" data-id=\"00551c2\" data-element_type=\"e-flexbox\" data-e-type=\"e-flexbox\" data-interaction-id=\"00551c2\">\n    \t\t<div class=\"elementor-element elementor-element-c6edf74 elementor-widget elementor-widget-text-editor\" data-id=\"c6edf74\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>Image 2 : Comparaison de l&rsquo;\u00e9mission par la vapeur d&rsquo;eau de l&rsquo;objet interstellaire (en noir) avec un mod\u00e8le (orange)<\/p><p>\u00a0<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\n<\/div>\n<div class=\"elementor-element elementor-element-72b19574 e-con-full e-flex e-con e-parent\" data-id=\"72b19574\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-53a7b892 e-con-full e-flex e-con e-child\" data-id=\"53a7b892\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-13a0d604 elementor-invisible elementor-widget elementor-widget-heading\" data-id=\"13a0d604\" data-element_type=\"widget\" data-e-type=\"widget\" data-settings=\"{&quot;_animation&quot;:&quot;fadeIn&quot;}\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Contacts<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-3108905 elementor-invisible elementor-widget elementor-widget-heading\" data-id=\"3108905\" data-element_type=\"widget\" data-e-type=\"widget\" data-settings=\"{&quot;_animation&quot;:&quot;fadeIn&quot;}\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">R\u00e9f\u00e9rents (scientifiques et techniques) <\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1c63b2a5 elementor-widget elementor-widget-text-editor\" data-id=\"1c63b2a5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<ul><li><strong><a href=\"https:\/\/www.ias.u-psud.fr\/pperso\/naghanim\/\">Nabila Aghanim<\/a>, Directrice de recherche, <span class=\"kY2IgmnCmOGjharHErah N56cWZpP8cNJu1dqgCxB\"><b>\u00c9<\/b><\/span>quipe Cosmologie<\/strong><\/li><li><strong><a href=\"https:\/\/www.ias.u-psud.fr\/htanimur\/\">Hideki Tanimura<\/a><\/strong><\/li><\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-fadb250 e-con-full e-flex e-con e-child\" data-id=\"fadb250\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-5640f83 elementor-invisible elementor-widget elementor-widget-heading\" data-id=\"5640f83\" data-element_type=\"widget\" data-e-type=\"widget\" data-settings=\"{&quot;_animation&quot;:&quot;fadeIn&quot;}\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">R\u00e9f\u00e9rences<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f6323b3 elementor-widget elementor-widget-text-editor\" data-id=\"f6323b3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<ul><li><a title=\"https:\/\/www.esa.int\/Science_Exploration\/Space_Science\/Juice\/Five_things_Juice_has_revealed_about_Comet_3I_ATLAS\" href=\"https:\/\/www.esa.int\/Science_Exploration\/Space_Science\/Juice\/Five_things_Juice_has_revealed_about_Comet_3I_ATLAS\">Communiqu\u00e9 de presse ESA<\/a><\/li><li><a title=\"https:\/\/cnes.fr\/communiques\/linstrument-majis-bord-de-mission-juice-croise-route-voyageur-interstellaire-3iatlas\" href=\"https:\/\/cnes.fr\/communiques\/linstrument-majis-bord-de-mission-juice-croise-route-voyageur-interstellaire-3iatlas\">Communiqu\u00e9 de presse CNES<\/a><\/li><li><a href=\"https:\/\/www.cnrs.fr\/fr\/presse\/quand-linstrument-majis-bord-de-la-mission-juice-croise-la-route-du-voyageur-interstellaire\">Communiqu\u00e9 de presse CNRS<\/a><\/li><li><a href=\"https:\/\/cnes.fr\/actualites\/juice-un-point-de-vue-unique-comete-3iatlas\">Interview du CNES<\/a><\/li><li><a href=\"https:\/\/www.universite-paris-saclay.fr\/actualites\/la-comete-interstellaire-3i\/atlas-observee-grace-la-mission-juice\" target=\"_blank\" rel=\"noopener\">Article de l&rsquo;Universit\u00e9 Paris-Saclay<\/a><\/li><\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>En novembre 2025, la mission Juice de l\u2019ESA a observ\u00e9 la com\u00e8te interstellaire 3I\/ATLAS, un visiteur rare venu d\u2019un autre syst\u00e8me stellaire.<\/p>\n","protected":false},"author":3,"featured_media":3401,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"elementor_header_footer","format":"standard","meta":{"inline_featured_image":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center 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