{"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\/fi\/the_universe\/","title":{"rendered":"Maailmankaikkeus"},"content":{"rendered":"
\n

Maailmankaikkeus on kaikkea sit\u00e4, mit\u00e4 voimme koskettaa, tuntea, aistia, mitata tai havaita. Siihen kuuluvat el\u00e4v\u00e4t olennot, planeetat, t\u00e4hdet, galaksit, p\u00f6lypilvet, valo ja jopa aika. Ennen maailmankaikkeuden synty\u00e4 aikaa, avaruutta ja ainetta ei ollut olemassa.<\/p>\n<\/div>\n

Maailmankaikkeudessa on miljardeja galakseja, joista jokainen sis\u00e4lt\u00e4\u00e4 miljoonia tai miljardeja t\u00e4hti\u00e4. T\u00e4htien ja galaksien v\u00e4linen tila on suurelta osin tyhj\u00e4. Kuitenkin jopa t\u00e4htien ja planeettojen kaukana olevissa paikoissa on hajallaan p\u00f6lyhiukkasia tai muutamia vetyatomeja kuutiosenttimetri\u00e4 kohti. Avaruus on my\u00f6s t\u00e4ynn\u00e4 s\u00e4teily\u00e4 (esim. valoa ja l\u00e4mp\u00f6\u00e4), magneettikentti\u00e4 ja suurenergisi\u00e4 hiukkasia (esim. kosmisia s\u00e4teit\u00e4).<\/p>\n

Maailmankaikkeus on uskomattoman valtava. Nykyaikaiselta h\u00e4vitt\u00e4j\u00e4lt\u00e4 kest\u00e4isi yli miljoona vuotta p\u00e4\u00e4st\u00e4 Auringon l\u00e4himp\u00e4\u00e4n t\u00e4hteen. Valon nopeudella (300 000 km sekunnissa) matkustaessa pelk\u00e4st\u00e4\u00e4n Linnunradan l\u00e4pi kulkeminen veisi 100 000 vuotta.<\/p>\n

Kukaan ei tied\u00e4 maailmankaikkeuden tarkkaa kokoa, koska emme n\u00e4e sen reunaa \u2013 jos sellaista edes on. Tied\u00e4mme vain, ett\u00e4 n\u00e4kyv\u00e4n maailmankaikkeuden halkaisija on v\u00e4hint\u00e4\u00e4n 93 miljardia valovuotta. (Valovuosi on et\u00e4isyys, jonka valo kulkee yhden vuoden aikana \u2013 noin 9 biljoonaa kilometri\u00e4.)<\/p>\n

Maailmankaikkeus ei ole aina ollut saman kokoinen. Tutkijat uskovat, ett\u00e4 se sai alkunsa suuresta alkur\u00e4j\u00e4hdyksest\u00e4, joka tapahtui l\u00e4hes 14 miljardia vuotta sitten. Siit\u00e4 l\u00e4htien maailmankaikkeus on laajentunut ulosp\u00e4in eritt\u00e4in suurella nopeudella. Siksi avaruuden alue, jonka nyt n\u00e4emme, on miljardeja kertoja suurempi kuin silloin, kun maailmankaikkeus oli viel\u00e4 hyvin nuori. My\u00f6s galaksit et\u00e4\u00e4ntyv\u00e4t toisistaan, kun niiden v\u00e4linen tila laajenee.<\/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\/fi\/wp-json\/wp\/v2\/posts\/197","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=197"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/197\/revisions"}],"predecessor-version":[{"id":1340,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/197\/revisions\/1340"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/media?parent=197"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/categories?post=197"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/tags?post=197"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/panel?post=197"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/language?post=197"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/age?post=197"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/duration?post=197"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/resource_type?post=197"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/audience?post=197"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/wf_post_folders?post=197"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}