{"id":953,"date":"2004-11-19T08:31:00","date_gmt":"2004-11-19T07:31:00","guid":{"rendered":"https:\/\/kids.esa.int\/telltale_signs\/"},"modified":"2026-10-08T00:34:10","modified_gmt":"2026-10-07T22:34:10","slug":"telltale_signs","status":"publish","type":"post","link":"https:\/\/kids.esa.int\/fi\/telltale_signs\/","title":{"rendered":"Selvi\u00e4 merkkej\u00e4"},"content":{"rendered":"
\n

Maa on ainoa tiedossamme oleva paikka, jossa el\u00e4m\u00e4 on mahdollista. Mik\u00e4 tekee siit\u00e4 niin erityisen? Yksi keskeinen tekij\u00e4 on nestem\u00e4isen veden olemassaolo. El\u00e4m\u00e4 Maassa n\u00e4ytt\u00e4\u00e4 saaneen alkunsa lammikoista tai merist\u00e4. Mik\u00e4\u00e4n el\u00e4m\u00e4 planeetallamme ei voi selviyty\u00e4 ilman vett\u00e4.<\/p>\n<\/div>\n

Maa on ainoa paikka aurinkokunnassamme, jonka pinnalla on laajoja valtameri\u00e4. T\u00e4m\u00e4 johtuu siit\u00e4, ett\u00e4 se sijaitsee \u2018Goldilocks\u2019-vy\u00f6hykkeell\u00e4.<\/p>\n

Venus on liian l\u00e4hell\u00e4 Aurinkoa ja liian kuuma. Mars on liian kaukana ja liian kylm\u00e4. Maapallolla on juuri oikea et\u00e4isyys ja oikea l\u00e4mp\u00f6tila.<\/p>\n

Voisiko muiden t\u00e4htien kiertoradalla olla \u2018Maita\u2019? Miten tunnistaisimme ne? Ensimm\u00e4iseksi on mitattava, kuinka kuuma tai kylm\u00e4 planeetta on. Lis\u00e4ksi pit\u00e4isi olla n\u00e4ytt\u00f6\u00e4 siit\u00e4, ett\u00e4 vett\u00e4 on runsaasti.<\/p>\n

Sitten meid\u00e4n on etsitt\u00e4v\u00e4 kaasuja, kuten happea ja metaania. N\u00e4m\u00e4 kaasut vapautuvat ilmaan el\u00e4vien olentojen toimesta.<\/p>\n

Tulevissa avaruusluotainmissioissa etsit\u00e4\u00e4n n\u00e4it\u00e4 \u2018biomarkkereita\u2019 tuhansista t\u00e4hti-planeetta-j\u00e4rjestelmist\u00e4. Vaikka ne eiv\u00e4t havaitse happea suoraan, ne \u2018n\u00e4kev\u00e4t\u2019 otsonia, joka on hapen muoto. Ne havaitsevat my\u00f6s hiilidioksidia, vett\u00e4 ja tietyiss\u00e4 tapauksissa metaania.<\/p>","protected":false},"excerpt":{"rendered":"

Earth is the only place we know that supports life. What makes it so special? One key factor is the presence of liquid water. Life on Earth seems to have […]<\/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\/2002\/01\/planet_earth_as_seen_by_the_apollo_17_astronauts2\/17863973-3-eng-GB\/Planet_Earth_as_seen_by_the_Apollo_17_astronauts.jpg","esa_banner_description":"Planet Earth as seen by the Apollo 17 astronauts","esa_banner_credit":"NASA","esa_banner_licence":"ESA Standard Licence","esa_banner_detail_url":"https:\/\/www.esa.int\/ESA_Multimedia\/Images\/2002\/01\/Planet_Earth_as_seen_by_the_Apollo_17_astronauts2","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":[14,10,13],"tags":[2],"panel":[],"language":[],"age":[],"duration":[],"resource_type":[],"audience":[],"wf_post_folders":[],"class_list":["post-953","post","type-post","status-publish","format-standard","hentry","category-are-we-alone","category-learn","category-life-in-space","tag-background-article"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/953","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=953"}],"version-history":[{"count":1,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/953\/revisions"}],"predecessor-version":[{"id":2096,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/posts\/953\/revisions\/2096"}],"wp:attachment":[{"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/media?parent=953"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/categories?post=953"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/tags?post=953"},{"taxonomy":"panel","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/panel?post=953"},{"taxonomy":"language","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/language?post=953"},{"taxonomy":"age","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/age?post=953"},{"taxonomy":"duration","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/duration?post=953"},{"taxonomy":"resource_type","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/resource_type?post=953"},{"taxonomy":"audience","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/audience?post=953"},{"taxonomy":"wf_post_folders","embeddable":true,"href":"https:\/\/kids.esa.int\/fi\/wp-json\/wp\/v2\/wf_post_folders?post=953"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}