{"id":182,"date":"2021-12-02T12:50:43","date_gmt":"2021-12-02T11:50:43","guid":{"rendered":"https:\/\/kids.esa.int\/planets_and_moons_exoplanets\/"},"modified":"2026-10-08T00:25:12","modified_gmt":"2026-10-07T22:25:12","slug":"planets_and_moons_exoplanets","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fi\/planets_and_moons_exoplanets\/","title":{"rendered":"Exoplaneetat"},"content":{"rendered":"<div class=\"lede\">\n<p>Se <a href=\"https:\/\/www.esa.int\/kids\/en\/learn\/Our_Universe\/Planets_and_moons\/The_Solar_System_and_its_planets\" target=\"_blank\" rel=\"noopener\">Aurinkokunta<\/a> sis\u00e4lt\u00e4\u00e4 kahdeksan planeettaa, jotka kiert\u00e4v\u00e4t paikallista t\u00e4htemme ymp\u00e4ri, <a href=\"https:\/\/www.esa.int\/kids\/en\/learn\/Our_Universe\/The_Sun\/Our_nearest_star\" target=\"_blank\" rel=\"noopener\">aurinko<\/a>. Mutta tiesitk\u00f6, ett\u00e4 avaruudessa on viel\u00e4 paljon, paljon enemm\u00e4n planeettoja, jotka kiert\u00e4v\u00e4t <a href=\"https:\/\/www.esa.int\/kids\/en\/learn\/Our_Universe\/Stars_and_galaxies\/Stars\" target=\"_blank\" rel=\"noopener\">t\u00e4hdet<\/a> joita n\u00e4emme y\u00f6ll\u00e4? Niit\u00e4 kutsutaan aurinkokunnan ulkopuolisiksi planeetoiksi, lyhyemmin eksoplaneetoiksi.<\/p>\n<p>Exoplaneettojen l\u00f6yt\u00e4minen on eritt\u00e4in vaikeaa. Ne ovat niin kaukana, ettemme voi yksinkertaisesti katsoa niit\u00e4 tavallisella kaukoputkella. Ne ovat my\u00f6s hyvin pieni\u00e4 ja himmeit\u00e4 verrattuna t\u00e4htiin, joiden kiertoradalla ne liikkuvat. T\u00e4m\u00e4 tarkoittaa, ett\u00e4 exoplaneettoja etsivien t\u00e4htitieteilij\u00f6iden on k\u00e4ytett\u00e4v\u00e4 kekseli\u00e4it\u00e4 menetelmi\u00e4!<\/p>\n<\/div>\n<p>Ensimm\u00e4inen menetelm\u00e4, jota t\u00e4htitieteilij\u00e4t k\u00e4yttiv\u00e4t eksoplaneettojen l\u00f6yt\u00e4miseen, tunnetaan nimell\u00e4 radiaalinen nopeus, mutta sill\u00e4 on yksinkertaisempi lempinimi: t\u00e4hden heilunta! Kun planeetta kiert\u00e4\u00e4 t\u00e4hte\u00e4, planeetan <a href=\"https:\/\/www.esa.int\/kids\/en\/learn\/Our_Universe\/Story_of_the_Universe\/Gravity\" target=\"_blank\" rel=\"noopener\">painovoima<\/a> vet\u00e4\u00e4 t\u00e4hte\u00e4 puoleensa, mink\u00e4 vuoksi meid\u00e4n n\u00e4k\u00f6kulmastamme n\u00e4ytt\u00e4\u00e4 silt\u00e4, kuin t\u00e4hti heiluisikin avaruudessa. Vaikutus on pieni, mutta eritt\u00e4in herkill\u00e4 mittalaitteilla voi olla mahdollista havaita joitakin eksoplaneettoja, jotka saavat t\u00e4htens\u00e4 heilumaan!<\/p>\n<p>Nyky\u00e4\u00e4n transit-menetelm\u00e4 on yleisempi havainnointitekniikka. Kun eksoplaneetta kulkee t\u00e4htens\u00e4 edest\u00e4, se saattaa peitt\u00e4\u00e4 pienen osan t\u00e4hden valosta. T\u00e4t\u00e4 kutsutaan transitiksi. Maasta katsottuna t\u00e4hti n\u00e4ytt\u00e4\u00e4 hieman himme\u00e4mm\u00e4lt\u00e4 transitin aikana ja kirkastuu j\u00e4lleen, kun planeetta ei en\u00e4\u00e4 peit\u00e4 valoa. T\u00e4m\u00e4 on vihje siit\u00e4, ett\u00e4 eksoplaneetta saattaa olla l\u00e4sn\u00e4! Transiitteja on haastavaa havaita, koska valon voimakkuuden muutos on niin pieni, mutta erityiset planeettojen etsint\u00e4\u00e4n tarkoitetut teleskoopit, kuten ESA:n <a href=\"https:\/\/sci.esa.int\/web\/corot\" target=\"_blank\" rel=\"noopener\">CoRoT<\/a> ovat olleet eritt\u00e4in menestyksekk\u00e4it\u00e4! ESA:n 2019 <a href=\"https:\/\/sci.esa.int\/web\/cheops\" target=\"_blank\" rel=\"noopener\">CHEOPS<\/a> My\u00f6s t\u00e4m\u00e4 teht\u00e4v\u00e4 hy\u00f6dynt\u00e4\u00e4 transit-menetelm\u00e4\u00e4.<\/p>\n<figure class=\"wp-block-image size-large\" data-width=\"2500\" data-credit=\"ESA\" data-detail-url=\"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2019\/02\/Transiting_exoplanet\" data-licence=\"ESA Standard Licence\" data-licence-url=\"https:\/\/www.esa.int\/ESA_Multimedia\/Terms_and_conditions_of_use_of_images_and_videos_available_on_the_esa_website\"><img decoding=\"async\" loading=\"lazy\" style=\"max-width:100%;height:auto\" src=\"https:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2019\/02\/transiting_exoplanet\/19220628-1-eng-GB\/Transiting_exoplanet.jpg\" alt=\"Transiting exoplanet\"><figcaption>Kiert\u00e4v\u00e4 eksoplaneetta<\/figcaption><\/figure>\n<p>Astrometria on toinen tekniikka, jota ESA:n <a href=\"https:\/\/sci.esa.int\/web\/gaia\" target=\"_blank\" rel=\"noopener\">Gaia<\/a> teht\u00e4v\u00e4. Y\u00f6ll\u00e4 voimme n\u00e4hd\u00e4 t\u00e4htien liikkuvan tiettyj\u00e4 reittej\u00e4 pitkin taivaallamme, ja voimme ennustaa niiden sijainnit eritt\u00e4in tarkasti monien vuosien ajalle. Jos t\u00e4hdell\u00e4 on planeetta, sen liike poikkeaa hieman odotetusta \u2013 vain hyvin v\u00e4h\u00e4n, mutta riitt\u00e4v\u00e4n paljon, jotta Gaia pystyy havaitsemaan sen!<\/p>\n<p>N\u00e4m\u00e4 ovat t\u00e4rkeimm\u00e4t menetelm\u00e4t aurinkokunnan ulkopuolisten planeettojen havaitsemiseksi, vaikka on olemassa my\u00f6s muita menetelmi\u00e4. Joskus on jopa mahdollista k\u00e4ytt\u00e4\u00e4 ammattimaisia observatorioita valokuvien ottamiseen \u2013 vaikka n\u00e4m\u00e4 kuvat vaikuttavatkin hyvin yksinkertaisilta verrattuna niihin kuviin, joita voimme ottaa l\u00e4heisist\u00e4 planeetoista omassa aurinkokunnassamme.<\/p>\n<figure class=\"wp-block-image size-large\" data-width=\"4042\" data-credit=\"ESA \u2013 SJM Photography\" data-detail-url=\"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2019\/10\/Children_imagine_exoplanets\" data-licence=\"ESA Standard Licence\" data-licence-url=\"https:\/\/www.esa.int\/ESA_Multimedia\/Terms_and_conditions_of_use_of_images_and_videos_available_on_the_esa_website\"><img decoding=\"async\" loading=\"lazy\" style=\"max-width:100%;height:auto\" src=\"https:\/\/www.esa.int\/var\/esa\/storage\/images\/esa_multimedia\/images\/2019\/10\/children_imagine_exoplanets\/20819272-1-eng-GB\/Children_imagine_exoplanets.jpg\" alt=\"Children imagine exoplanets\"><figcaption>Lapset kuvittelevat eksoplaneettoja<\/figcaption><\/figure>\n<p>N\u00e4iden menetelmien avulla on t\u00e4h\u00e4n menness\u00e4 l\u00f6ydetty tuhansia aurinkokunnan ulkopuolisia planeettoja, ja l\u00f6yd\u00e4mme niit\u00e4 koko ajan lis\u00e4\u00e4. Voisiko jollakin n\u00e4ist\u00e4 planeetoista olla el\u00e4m\u00e4\u00e4? Ehk\u00e4 jopa <a href=\"https:\/\/www.esa.int\/kids\/en\/learn\/Life_in_Space\/Are_we_alone\/Are_we_alone\" target=\"_blank\" rel=\"noopener\">\u00e4lykk\u00e4\u00e4t olennot<\/a> Pid\u00e4tk\u00f6 meist\u00e4? Mit\u00e4 mielt\u00e4 olet?<\/p>\n<p>T\u00e4m\u00e4 on todellakin eritt\u00e4in j\u00e4nnitt\u00e4v\u00e4 aika niille, jotka ovat kiinnostuneita eksoplaneetoista!<\/p>","protected":false},"excerpt":{"rendered":"<p>The Solar System contains eight planets orbiting our local star, the Sun. But did you know that there are many, many more planets out there in space, orbiting the stars [&hellip;]<\/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\/2019\/09\/hubble_finds_water_vapor_on_habitable-zone_exoplanet_for_the_first_time\/19700242-1-eng-GB\/Hubble_Finds_Water_Vapor_on_Habitable-Zone_Exoplanet_for_the_First_Time.jpg","esa_banner_description":"We do not yet have the technology to take detailed photos of exoplanets, but an artist created this picture of what one may look like. Copyright: ESA\/Hubble, M. Kornmesser","esa_banner_credit":"ESA\/Hubble, M. Kornmesser","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2019\/09\/Hubble_finds_water_vapor_on_habitable-zone_exoplanet_for_the_first_time","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":[10,11,12],"tags":[2],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-182","post","type-post","status-publish","format-standard","hentry","category-learn","category-our-universe","category-planets-and-moons","tag-background-article"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/182","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/comments?post=182"}],"version-history":[{"count":5,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/182\/revisions"}],"predecessor-version":[{"id":4346,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/182\/revisions\/4346"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/media?parent=182"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/categories?post=182"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/tags?post=182"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/panel?post=182"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/language?post=182"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/age?post=182"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/duration?post=182"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/resource_type?post=182"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/audience?post=182"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/wf_post_folders?post=182"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}