{"id":705,"date":"2012-10-29T08:57:00","date_gmt":"2012-10-29T07:57:00","guid":{"rendered":"https:\/\/kids.esa.int\/new_satellite_to_study_alien_planets\/"},"modified":"2026-10-08T00:31:20","modified_gmt":"2026-10-07T22:31:20","slug":"new_satellite_to_study_alien_planets","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fr\/new_satellite_to_study_alien_planets\/","title":{"rendered":"Un nouveau satellite pour l\u2019\u00e9tude des plan\u00e8tes extrasolaires"},"content":{"rendered":"
\n

Depuis la Terre, on peut parfois observer V\u00e9nus et Mercure sous la forme de taches noires traversant le Soleil. Lors de ces ph\u00e9nom\u00e8nes \u2013 appel\u00e9s \u00ab transits \u00bb \u2013, la plan\u00e8te bloque une infime partie de la lumi\u00e8re, ce qui rend le Soleil l\u00e9g\u00e8rement moins brillant. Des ph\u00e9nom\u00e8nes d\u2019att\u00e9nuation similaires peuvent \u00eatre provoqu\u00e9s par des exoplan\u00e8tes, ces mondes qui orbitent autour d\u2019\u00e9toiles plus lointaines. L\u2019ESA a d\u00e9sormais d\u00e9cid\u00e9 de mettre en place une nouvelle mission scientifique afin de rechercher ces transits.<\/p>\n<\/div>\n

Le lancement de cette mission, baptis\u00e9e Cheops (pour CHaracterising ExOPlanets Satellite, ou \u00ab satellite de caract\u00e9risation des exoplan\u00e8tes \u00bb), est pr\u00e9vu pour 2017. Cheops s\u2019int\u00e9ressera plus particuli\u00e8rement aux \u00e9toiles brillantes et proches figurant au c\u0153ur d\u2019un syst\u00e8me plan\u00e9taire. Le satellite surveillera avec pr\u00e9cision la luminosit\u00e9 de chaque \u00e9toile pour rep\u00e9rer le moindre signe d\u2019un transit.<\/p>\n

\"Planet
Passage d'une plan\u00e8te devant une \u00e9toile<\/figcaption><\/figure>\n

Gr\u00e2ce \u00e0 des observations d\u00e9taill\u00e9es des changements de luminosit\u00e9, on pourra calculer pr\u00e9cis\u00e9ment le rayon de chaque plan\u00e8te en transit. Pour les plan\u00e8tes dont on conna\u00eet d\u00e9j\u00e0 la masse, c\u2019est leur densit\u00e9 que l\u2019on pourra conna\u00eetre, laquelle fournira des indications sur leur structure interne.<\/p>\n

Les donn\u00e9es sur la taille et la masse des exoplan\u00e8tes aideront les chercheurs \u00e0 comprendre le processus de formation d\u2019un large \u00e9ventail de plan\u00e8tes, depuis les \u00ab super-Terres \u00bb, dont la taille est \u00e9quivalente \u00e0 plusieurs fois celle de la Terre, jusqu\u2019\u00e0 des plan\u00e8tes aussi imposantes que Neptune. Par ailleurs, cette mission permettra d\u2019identifier les plan\u00e8tes dot\u00e9es d\u2019une atmosph\u00e8re significative, puis de les \u00e9tudier de mani\u00e8re d\u00e9taill\u00e9e gr\u00e2ce \u00e0 la prochaine g\u00e9n\u00e9ration de t\u00e9lescopes. Ces nouveaux dispositifs incluent le t\u00e9lescope terrestre EELT (European Extremely Large Telescope) et le t\u00e9lescope spatial James Webb.<\/p>\n

CHEOPS est d\u00e9velopp\u00e9 conjointement par l\u2019ESA, la Suisse et certains autres \u00e9tats membres de l\u2019ESA. Le satellite sera plac\u00e9 sur une orbite quasi polaire, \u00e0 800 km au-dessus de la Terre. La dur\u00e9e de son service sera de trois ans et demi.<\/p>","protected":false},"excerpt":{"rendered":"

From Earth, we can sometimes see Venus and Mercury as black spots passing across the Sun. During such events \u2013 called transits – the planet blocks a tiny amount of […]<\/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\/2012\/10\/artist_impression_of_cheops2\/17900088-2-eng-GB\/Artist_impression_of_Cheops.jpg","esa_banner_description":"Artist impression of Cheops","esa_banner_credit":"University of Bern","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2012\/10\/Artist_impression_of_Cheops2","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":[26],"tags":[],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-705","post","type-post","status-publish","format-standard","hentry","category-news"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/posts\/705","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=705"}],"version-history":[{"count":4,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/posts\/705\/revisions"}],"predecessor-version":[{"id":4640,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/posts\/705\/revisions\/4640"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/media?parent=705"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/categories?post=705"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/tags?post=705"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/panel?post=705"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/language?post=705"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/age?post=705"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/duration?post=705"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/resource_type?post=705"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/audience?post=705"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fr\/wp-json\/wp\/v2\/wf_post_folders?post=705"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}