{"id":632,"date":"2022-05-21T19:06:38","date_gmt":"2022-05-21T17:06:38","guid":{"rendered":"http:\/\/www.cosmoespai.com\/cat\/?p=632"},"modified":"2022-05-21T19:06:38","modified_gmt":"2022-05-21T17:06:38","slug":"on-comenca-lespai","status":"publish","type":"post","link":"https:\/\/www.cosmoespai.com\/cat\/on-comenca-lespai\/","title":{"rendered":"On comen\u00e7a l\u2019espai?"},"content":{"rendered":"\n<p class=\"has-text-align-justify\">Tot i semblar una preguntar senzilla, l\u2019altura en la qual comen\u00e7a l\u2019espai no est\u00e0 del tot clara, i les definicions sobre la frontera entre l\u2019atmosfera i l\u2019espai poden variar segons la font. En efecte, no hi ha un punt espec\u00edfic on acabi l\u2019atmosfera, sin\u00f3 que aquesta es va fent cada cop m\u00e9s menys densa, fins a arribar a un punt en qu\u00e8 desapareix.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><em><u><strong>La definici\u00f3 m\u00e9s acceptada<\/strong><\/u><\/em><\/h4>\n\n\n\n<p class=\"has-text-align-justify\">La definici\u00f3 m\u00e9s acceptada del \u00abcomen\u00e7ament de l\u2019espai\u00bb \u00e9s la que el situa a 100 kil\u00f2metres (unes 62 milles) sobre el nivell del mar. Aquesta altura \u00e9s coneguda com la l\u00ednia de K\u00e1rm\u00e1n, en honor al f\u00edsic i enginyer hongar\u00e8s Theodore von K\u00e1rm\u00e1n.<\/p>\n\n\n\n<p class=\"has-text-align-justify\">Aquest f\u00edsic va determinar que l\u2019aeron\u00e0utica ja no funcionaria a aquesta altura. En altres paraules, la l\u00ednia de K\u00e1rm\u00e1n \u00e9s l\u2019altura en la que una aeronau no pot volar, ja que la densitat de l\u2019aire \u00e9s tan baixa que l\u2019avi\u00f3 no podria generar un impuls vertical, necessari per volar.<\/p>\n\n\n\n<p class=\"has-text-align-justify\">La F\u00e9d\u00e9ration A\u00e9ronautique Internationale (FAI), l\u2019organisme internacional que estableix normes i mant\u00e9 r\u00e8cords en els camps de l\u2019aeron\u00e0utica i astron\u00e0utica, situa el comen\u00e7ament de l\u2019espai a una altura de 100 kil\u00f2metres, seguint fidels a la l\u00ednia de K\u00e1rm\u00e1n.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><em><u><strong>Unes propostes alternatives<\/strong><\/u><\/em><\/h4>\n\n\n\n<p class=\"has-text-align-justify\">Malgrat aix\u00f2, els 100 kil\u00f2metres de la l\u00ednia de K\u00e1rm\u00e1n s\u00f3n d\u2019alguna manera arbitraris i no s\u00f3n acceptats per tothom. Per exemple, la FAA (Federal Aviation Authority), dels Estats Units, afirma que l\u2019espai comen\u00e7a a una altura de 80 kil\u00f2metres per sobre del nivell del mar, i no a la l\u00ednia de K\u00e1rm\u00e1n. D\u2019aquesta manera, atorga l\u2019estatus d\u2019astronauta a aquells que sobrepassin aquesta altura de 80 kil\u00f2metres (o 50 milles). Aquest estatus d\u2019astronauta s\u2019aplica als empleats de la NASA, aix\u00ed com al personal militar que arribi a aquesta altura.<\/p>\n\n\n\n<p class=\"has-text-align-justify\">Encara hi ha altres criteris sobre el comen\u00e7ament de l\u2019espai, incloent la rapidesa amb la que es mouen els ions presents a l\u2019atmosfera. Altres persones consideren que l\u2019espai comen\u00e7a quan una nau es troba en \u00f2rbita al voltant de la Terra&#8230;<\/p>\n\n\n\n<p class=\"has-text-align-justify\">En conclusi\u00f3, no hi ha un punt fixe en el que considerem que comen\u00e7a l\u2019espai. Cadascuna de les definicions per al comen\u00e7ament de l\u2019espai dep\u00e8n dels processos a l\u2019atmosfera terrestre que considerem importants: el punt on un avi\u00f3 ja no pot volar, arribar a l\u2019\u00f2rbita terrestre, etc.<\/p>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<p><strong>Entrades Similars:<\/strong><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/per-que-a-la-muntanya-fa-mes-fred-que-al-nivell-del-mar\/\">Per qu\u00e8 a la muntanya fa m\u00e9s fred que al nivell del mar?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/per-que-el-cel-de-nit-es-fosc\/\">Per qu\u00e8 el cel de nit \u00e9s fosc?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/que-es-la-velocitat-descapament\/\">Qu\u00e8 \u00e9s la velocitat d\u2019escapament?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/com-sabem-que-lunivers-sesta-expandint\/\">Com sabem que l\u2019univers s\u2019est\u00e0 expandint?<\/a><\/p>\n\n\n\n<p><strong>Entrades Populars:<\/strong><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/perque-la-lluna-nomes-ens-ensenya-una-cara\/\">Perqu\u00e8 la Lluna nom\u00e9s ens ensenya una cara?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/stephenson-2-18-lestrella-mes-gran-coneguda-a-lunivers\/\">Stephenson 2-18, l\u2019estrella m\u00e9s gran coneguda a l\u2019univers<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/lexplotacio-minera-al-cinturo-dasteroides-una-font-de-recursos\/\">L\u2019explotaci\u00f3 minera al cintur\u00f3 d\u2019asteroides, una font de recursos<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/la-brossa-espacial-un-gran-problema\/\">La brossa espacial, un gran problema<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/com-es-van-extingir-els-dinosaures\/\">Com es van extingir els dinosaures?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/que-passaria-si-la-terra-deixes-de-rotar\/\">Qu\u00e8 passaria si la Terra deix\u00e9s de rotar?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/la-missio-a-venus-de-la-sonda-venus-express-per-la-esa\/\">La missi\u00f3 a Venus de la sonda Venus Express per la ESA<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/quins-son-els-requisits-per-a-ser-un-planeta\/\">Quins s\u00f3n els requisits per a ser un planeta?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/perque-no-es-poden-sentir-sons-a-lespai\/\">Perqu\u00e8 no es poden sentir sons a l\u2019espai?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/quina-mida-i-forma-tindrien-els-extraterrestres\/\">Quina mida i forma tindrien els extraterrestres?<\/a><\/p>\n\n\n\n<p><a href=\"http:\/\/www.cosmoespai.com\/cat\/les-unitats-de-mesura-que-fem-servir-en-astronomia\/\">Les unitats de mesura que fem servir en astronomia<\/a><\/p>\n\n\n\n<p><strong>Entrades Recents:<\/strong><\/p>\n\n\n<ul class=\"wp-block-latest-posts__list is-grid columns-3 wp-block-latest-posts\"><li><a class=\"wp-block-latest-posts__post-title\" href=\"https:\/\/www.cosmoespai.com\/cat\/com-viatjar-al-futur-sense-violar-les-lleis-de-la-fisica\/\">Com Viatjar al Futur Sense Violar les Lleis de la F\u00edsica<\/a><\/li>\n<li><a class=\"wp-block-latest-posts__post-title\" href=\"https:\/\/www.cosmoespai.com\/cat\/que-es-la-gravetat\/\">Qu\u00e8 \u00e9s la gravetat?<\/a><\/li>\n<li><a class=\"wp-block-latest-posts__post-title\" href=\"https:\/\/www.cosmoespai.com\/cat\/per-que-hi-ha-mes-materia-que-antimateria-a-lunivers\/\">Per qu\u00e8 hi ha m\u00e9s mat\u00e8ria que antimat\u00e8ria a l\u2019univers?<\/a><\/li>\n<li><a class=\"wp-block-latest-posts__post-title\" href=\"https:\/\/www.cosmoespai.com\/cat\/que-es-lantimateria\/\">Qu\u00e8 \u00e9s l\u2019antimat\u00e8ria?<\/a><\/li>\n<li><a class=\"wp-block-latest-posts__post-title\" href=\"https:\/\/www.cosmoespai.com\/cat\/per-que-els-centres-de-les-galaxies-contenen-forats-negres\/\">Per qu\u00e8 els centres de les gal\u00e0xies contenen forats negres?<\/a><\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>Tot i semblar una preguntar senzilla, l\u2019altura en la qual comen\u00e7a l\u2019espai no est\u00e0 del tot clara, i les definicions sobre la frontera entre l\u2019atmosfera<span class=\"read-more-link\"><a class=\"read-more\" href=\"https:\/\/www.cosmoespai.com\/cat\/on-comenca-lespai\/\">Continuar llegint<\/a><\/span><\/p>\n","protected":false},"author":1,"featured_media":635,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_mi_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":""},"categories":[1,6],"tags":[571,218,551,573],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/05\/Comen\u00e7ament_Espai.jpg?fit=720%2C405","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":419,"url":"https:\/\/www.cosmoespai.com\/cat\/el-supervolca-de-yellowstone-un-gran-perill-per-la-humanitat\/","url_meta":{"origin":632,"position":0},"title":"El supervolc\u00e0 de Yellowstone, un gran perill per la humanitat","author":"Ferran","date":"6 d'agost de 2021","format":false,"excerpt":"Al nostre planeta hi ha volcans, i supervolcans. Aquests \u00faltims no tenen una definici\u00f3 que tothom accepti, per\u00f2 en el que s\u00ed que tothom est\u00e0 d\u2019acord, \u00e9s en que provoquen cat\u00e0strofes a nivell mundial. Molts cient\u00edfics utilitzen aquest terme per referir-se a erupcions d\u2019una viol\u00e8ncia i magnituds excepcionals. A la\u2026","rel":"","context":"A &quot;La Terra&quot;","block_context":{"text":"La Terra","link":"https:\/\/www.cosmoespai.com\/cat\/category\/sistema-solar\/la-terra\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2021\/08\/Super-volc\u00e0_Yellowstone.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2021\/08\/Super-volc\u00e0_Yellowstone.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2021\/08\/Super-volc\u00e0_Yellowstone.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2021\/08\/Super-volc\u00e0_Yellowstone.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":836,"url":"https:\/\/www.cosmoespai.com\/cat\/on-esta-el-centre-de-lunivers\/","url_meta":{"origin":632,"position":1},"title":"On est\u00e0 el centre de l\u2019univers?","author":"Ferran","date":"15 de gener de 2023","format":false,"excerpt":"Fins fa uns segles, tothom creia que la Terra era el centre de l\u2019univers, i que tot orbitava al voltant de nosaltres. Aquesta visi\u00f3 de l\u2019univers va canviar gr\u00e0cies a Cop\u00e8rnic, i no ha parat d\u2019evolucionar des de llavors. Avui en dia sabem que l\u2019univers no t\u00e9 cap centre. Segons\u2026","rel":"","context":"A &quot;Univers&quot;","block_context":{"text":"Univers","link":"https:\/\/www.cosmoespai.com\/cat\/category\/univers\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/01\/Centre_Univers.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/01\/Centre_Univers.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/01\/Centre_Univers.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2023\/01\/Centre_Univers.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":168,"url":"https:\/\/www.cosmoespai.com\/cat\/el-relleu-de-mart-molt-mes-accidentat-que-el-de-la-terra\/","url_meta":{"origin":632,"position":2},"title":"El relleu de Mart, molt m\u00e9s accidentat que el de la Terra","author":"Ferran","date":"20 de setembre de 2020","format":false,"excerpt":"Mart t\u00e9 relleus molt semblants als de la Terra, per\u00f2 en unes dimensions molt diferents. Mart t\u00e9 les muntanyes, els volcans i les gorges m\u00e9s grans del sistema solar. El Mont Olimp Un d\u2019aquests volcans \u00e9s el \u00abMont Olimp\u00bb. El Mont Olimp \u00e9s el volc\u00e0 m\u00e9s gran del sistema solar.\u2026","rel":"","context":"A &quot;Mart&quot;","block_context":{"text":"Mart","link":"https:\/\/www.cosmoespai.com\/cat\/category\/sistema-solar\/mart\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/09\/Relleu_Mart.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/09\/Relleu_Mart.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/09\/Relleu_Mart.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/09\/Relleu_Mart.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":691,"url":"https:\/\/www.cosmoespai.com\/cat\/el-new-shepard-un-coet-pel-turisme-espacial\/","url_meta":{"origin":632,"position":3},"title":"El New Shepard, un coet pel turisme espacial","author":"Ferran","date":"24 de juliol de 2022","format":false,"excerpt":"El New Shepard \u00e9s un coet fabricat per Blue Origin, una empresa aeroespacial fundada a l\u2019any 2000 per Jeff Bezos, propietari i fundador d\u2019Amazon. Aquest coet est\u00e0 destinat al turisme espacial, i est\u00e0 dissenyat per portar 6 persones en un vol suborbital, durant el qual arriba fins a uns 100\u2026","rel":"","context":"A &quot;Coets&quot;","block_context":{"text":"Coets","link":"https:\/\/www.cosmoespai.com\/cat\/category\/coets\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/07\/New_Shepard.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/07\/New_Shepard.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/07\/New_Shepard.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/07\/New_Shepard.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":642,"url":"https:\/\/www.cosmoespai.com\/cat\/biografia-de-stephen-hawking\/","url_meta":{"origin":632,"position":4},"title":"Biografia de Stephen Hawking","author":"Ferran","date":"4 de juny de 2022","format":false,"excerpt":"Stephen Hawking va ser un important f\u00edsic te\u00f2ric brit\u00e0nic, que durant gran part de la seva vida va sofrir d\u2019una discapacitat motora neuronal que li impedia la mobilitat. Va n\u00e9ixer el 8 de gener de 1942 a Oxford, Anglaterra, exactament 300 anys despr\u00e9s de la mort de Galileu, que va\u2026","rel":"","context":"A &quot;General&quot;","block_context":{"text":"General","link":"https:\/\/www.cosmoespai.com\/cat\/category\/general\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/06\/Biografia_Hawking.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/06\/Biografia_Hawking.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/06\/Biografia_Hawking.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2022\/06\/Biografia_Hawking.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]},{"id":115,"url":"https:\/\/www.cosmoespai.com\/cat\/una-nau-que-viatja-mes-rapid-que-la-llum\/","url_meta":{"origin":632,"position":5},"title":"Una nau que viatja m\u00e9s r\u00e0pid que la llum?","author":"Ferran","date":"20 de juliol de 2020","format":false,"excerpt":"Un dia, mentre mirava la tele, el f\u00edsic te\u00f2ric mexic\u00e0 Miguel Alcubierre, es va fascinar mirant un episodi de Star Trek en el qual l\u2019Enterprise aconseguia anar a unes velocitats m\u00e9s altes que les de la llum. D\u2019alguna manera aconseguia comprimir l\u2019espai-temps que hi havia davant seu, fent que les\u2026","rel":"","context":"A &quot;Univers&quot;","block_context":{"text":"Univers","link":"https:\/\/www.cosmoespai.com\/cat\/category\/univers\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/07\/Nau_Alcubierre.jpg?fit=720%2C405&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/07\/Nau_Alcubierre.jpg?fit=720%2C405&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/07\/Nau_Alcubierre.jpg?fit=720%2C405&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.cosmoespai.com\/cat\/wp-content\/uploads\/2020\/07\/Nau_Alcubierre.jpg?fit=720%2C405&resize=700%2C400 2x"},"classes":[]}],"_links":{"self":[{"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/posts\/632"}],"collection":[{"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/comments?post=632"}],"version-history":[{"count":2,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/posts\/632\/revisions"}],"predecessor-version":[{"id":634,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/posts\/632\/revisions\/634"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/media\/635"}],"wp:attachment":[{"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/media?parent=632"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/categories?post=632"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cosmoespai.com\/cat\/wp-json\/wp\/v2\/tags?post=632"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}