{"id":923,"date":"2004-11-16T10:04:00","date_gmt":"2004-11-16T09:04:00","guid":{"rendered":"https:\/\/kids.esa.int\/exploring_asteroids\/"},"modified":"2026-10-08T00:33:49","modified_gmt":"2026-10-07T22:33:49","slug":"exploring_asteroids","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fi\/exploring_asteroids\/","title":{"rendered":"Asteroidien tutkiminen"},"content":{"rendered":"
\n

Suurin osa asteroideista on niin pieni\u00e4 ja niin kaukana, ett\u00e4 n\u00e4emme ne vain pienin\u00e4 valopistein\u00e4. Ne havaitaan niiden liikkeen perusteella, kun ne kulkevat y\u00f6taivaan \u2018kiinteiden t\u00e4htien\u2019 edest\u00e4. Saamme lis\u00e4tietoa niist\u00e4 tutkimalla niiden heijastamaa valoa suurten teleskooppien avulla.<\/p>\n<\/div>\n

Jopa Hubble-avaruusteleskooppi ei kuitenkaan pysty paljastamaan niist\u00e4 paljoakaan. Yksi mielenkiintoisimmista asteroideista on metallipitoinen Vesta. Hubblen kuvissa n\u00e4kyy melko py\u00f6re\u00e4 kappale, jossa on suuri t\u00f6rm\u00e4yskraatteri.<\/p>\n

Joitakin maata hipovia asteroideja on tutkittu tutkan avulla. Suuret radioteleskoopit havaitsevat tutkan heijastukset, joiden avulla selvitet\u00e4\u00e4n asteroidien muoto ja koko.<\/p>\n

Muutamia asteroideja on tutkittu tarkemmin niille saapuneiden avaruusalusten avulla. Kuvissa n\u00e4kyy kohteita, joissa on lukuisia kraattereita, mik\u00e4 osoittaa, ett\u00e4 ne ovat joutuneet t\u00f6rm\u00e4ysten kohteeksi miljardien vuosien aikana. Vuonna 2000 NEAR Shoemakerista tuli ensimm\u00e4inen avaruusalus, joka siirtyi kiertoradalle asteroidin ymp\u00e4rille. Avaruusalus p\u00e4\u00e4tti toimintansa tekem\u00e4ll\u00e4 historiallisen laskeutumisen Erosille, joka on yksi suurimmista Maan l\u00e4hell\u00e4 olevista asteroideista.<\/p>\n

My\u00f6s ESAn Rosetta-avaruusluotain on ohittanut matkallaan komeettaan kaksi p\u00e4\u00e4vy\u00f6hykkeen asteroidia \u2013 Steinsin ja Lutetian. Halkaisijaltaan noin 130 km:n Lutetia oli suurin asteroidi, jolla avaruusluotain on t\u00e4h\u00e4n menness\u00e4 vieraillut. ESA tutkii my\u00f6s keinoja, joilla kohti Maata suuntaavan asteroidin kurssia voitaisiin muuttaa.<\/p>","protected":false},"excerpt":{"rendered":"

Most asteroids are so small and so far away that we can only see them as tiny points of light. They are found through their movement in front 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\/2003\/04\/asteroids_come_in_many_shapes_and_sizes2\/17886580-2-eng-GB\/Asteroids_come_in_many_shapes_and_sizes.jpg","esa_banner_description":"Asteroids come in many shapes and sizes","esa_banner_credit":"courtesy Observatoire de Paris","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2003\/04\/Asteroids_come_in_many_shapes_and_sizes2","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":[46,10,11],"tags":[2],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-923","post","type-post","status-publish","format-standard","hentry","category-comets-and-meteors","category-learn","category-our-universe","tag-background-article"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/923","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=923"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/923\/revisions"}],"predecessor-version":[{"id":2066,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/923\/revisions\/2066"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/media?parent=923"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/categories?post=923"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/tags?post=923"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/panel?post=923"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/language?post=923"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/age?post=923"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/duration?post=923"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/resource_type?post=923"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/audience?post=923"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/wf_post_folders?post=923"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}