{"id":2897,"date":"2025-11-02T16:35:10","date_gmt":"2025-11-02T14:35:10","guid":{"rendered":"https:\/\/zoobrasov.ro\/planetariu\/?p=2897"},"modified":"2025-11-02T16:35:10","modified_gmt":"2025-11-02T14:35:10","slug":"migrarea-planetelor-si-formarea-sistemului-solar","status":"publish","type":"post","link":"https:\/\/zoobrasov.ro\/planetariu\/migrarea-planetelor-si-formarea-sistemului-solar\/","title":{"rendered":"Migrarea planetelor \u0219i formarea Sistemului Solar"},"content":{"rendered":"<h3 align=\"left\"><span style=\"font-size: 120%; color: #000000;\">Scenariul \u201estandard\u201d al form\u0103rii planetare presupune faptul c\u0103 acestea se formeaz\u0103 treptat, pas cu pas, urm\u00e2nd o succesiune de procese distincte. Modelul a fost dezvoltat \u00een anii 1960 &#8211; 1970, pe baza ideilor fizicianului rus Victor Safronov. <\/span><\/h3>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">\u00cen Sistemul Solar avem 8 planete \u0219i toate <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">cele 8 planete orbiteaz\u0103 aproximativ \u00een acela\u0219i plan \u0219i, \u00een plus, \u00een aceea\u0219i direc\u021bie. De asemenea, acest plan \u0219i aceast\u0103 direc\u021bie corespund axei \u0219i sensului de rota\u021bie al Soarelui. Acest simplu fapt sus\u021bine puternic ideea unei origini comune pentru toate planetele, o origine care este probabil legat\u0103 \u0219i de originea Soarelui \u00eensu\u0219i. De exemplu, dac\u0103 Soarele ar fi capturat planetele una c\u00e2te una, nu ar exista nicio ra\u021biune pentru care acestea s\u0103 fie toate \u00een acela\u0219i plan. <\/span><\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Trebuie s\u0103 nu uit\u0103m <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">c\u0103 peste 99,8% din masa total\u0103 a sistemului solar se afl\u0103 \u00een Soare, planetele reprezent\u00e2nd doar o foarte mic\u0103 frac\u021biune din aceasta. Pe de alt\u0103 parte, majoritatea momentului cinetic al sistemului solar (pentru a schematiza, energia sa de rota\u021bie) este con\u021binut\u0103 \u00een planete, Soarele av\u00e2nd doar 1% din momentul total.<\/span><\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">O prim\u0103 privire, chiar \u0219i superficial\u0103, asupra planetelor sistemului solar arat\u0103 c\u0103 acestea pot fi \u00eemp\u0103r\u021bite \u00een 2 grupuri bine distincte: cele 4 planete terestre, mici \u0219i apropiate de Soare, \u0219i cele 4 planete gigantice, mult mai masive \u0219i situate \u00een regiunile externe \u0219i reci. Planetele terestre au mase cuprinse \u00eentre 0,06 \u0219i 1, sunt \u00een esen\u021b\u0103 st\u00e2ncoase \u0219i sunt foarte s\u0103race \u00een hidrogen \u0219i heliu, cele dou\u0103 elemente cele mai abundente din Univers. \u00cen schimb, planetele gigantice au mase cuprinse \u00eentre 15 (Uranus) \u0219i 300 (Jupiter) mase terestre. Printre aceste gigantice trebuie s\u0103 distingem mai \u00eent\u00e2i cele dou\u0103 \u201egazoase\u201d, Jupiter \u0219i Saturn, <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">formate <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">\u00een principal <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">din <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">H<\/span><\/span><\/span><sub><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">2<\/span><\/span><\/span><\/sub><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> \u0219i He gazos; totu\u0219i, ele con\u021bin \u00eentre 10% \u0219i 50% solide sub form\u0103 de roci \u0219i ghea\u021b\u0103 (probabil concentrate \u00eentr-un nucleu solid). Urmeaz\u0103 apoi giganticele \u201e\u00eenghe\u021bate\u201d, Uranus \u0219i Neptun, <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">formate \u00een principal<\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> de ghea\u021b\u0103 (ap\u0103, amoniac \u0219i metan), dar care au totu\u0219i o atmosfer\u0103 ce con\u021bine \u00eentre 1% \u0219i 5% H<\/span><\/span><\/span><sub><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">2<\/span><\/span><\/span><\/sub><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> \u0219i He.<\/span><\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">De asemenea, cercet\u00e2nd \u0219i analiz\u00e2nd meteori\u021bii din categoria condritelor, al c\u0103ror interior nu a fost alterat, s-a putut data v\u00e2rsta Sistemului Solar care este de 4,568 mld de ani. Dat\u00e2nd \u0219i micile intruziuni de zirconiu din rocile de pe Terra sau rocile aduse de pe Lun\u0103, s-a tras concluzia c\u0103 P\u0103m\u00e2ntul a avut nevoie de maximum 150 de milioane de ani pentru a se forma, asta \u00eenseamn\u0103 c\u0103 orice scenariu de formare a planetelor nu prea poate dep\u0103\u0219i aceast\u0103 m\u0103sur\u0103toare.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><strong><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Formarea Soarelui<\/span><\/span><\/span><\/span><\/strong><\/p>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">O stea se formeaz\u0103 prin colapsul gravita\u021bional al unui nor molecular, un amestec de micro-particule de praf, de gaz \u0219i de molecule cu o densitate \u00een jurul a 10<\/span><\/span><\/span><sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">3<\/span><\/span><\/span><\/sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> particule pe cm<\/span><\/span><\/span><sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">3<\/span><\/span><\/span><\/sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> (o densitate foarte mic\u0103, g\u00e2ndi\u021bi-v\u0103, atmosfera are undeva la 10<\/span><\/span><\/span><sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">19<\/span><\/span><\/span><\/sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">\/cm<\/span><\/span><\/span><sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">3<\/span><\/span><\/span><\/sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">) \u0219i cu temperaturi foarte sc\u0103zute de 10 &#8211; 150 K.<\/span><\/span><\/span><\/span><\/p>\n<p align=\"left\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2900 aligncenter\" src=\"https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-ss.jpg\" alt=\"\" width=\"654\" height=\"433\" srcset=\"https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-ss.jpg 1554w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-ss-300x199.jpg 300w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-ss-1024x679.jpg 1024w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-ss-768x509.jpg 768w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-ss-1536x1018.jpg 1536w\" sizes=\"auto, (max-width: 654px) 100vw, 654px\" \/><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Un nor molecular se plimb\u0103 lini\u0219tit prin galaxie p\u00e2n\u0103 e destabilizat, p\u00e2n\u0103 ceva \u00eel scoate din amor\u021beal\u0103 s\u0103 zicem. Instabilitatea asta gravita\u021bional\u0103 e declan\u0219at\u0103 de coliziunea cu al\u021bi nori moleculari, de explozii de stele, de coliziuni dintre galaxii, astfel c\u0103 norul \u00eencepe s\u0103 se \u201dcomprime\u201d sub propria greutate, energia gravita\u021bional\u0103 fiind transformat\u0103 \u00een c\u0103ldur\u0103. \u00cen procesul de comprimare, se \u0219i fragmenteaz\u0103. Anumite zone ajung la faza protostelar\u0103, cu o zon\u0103 intern\u0103 care continu\u0103 s\u0103 se contracte \u0219i s\u0103 se \u00eenc\u0103lzeasc\u0103, cu un disc de acre\u021bie \u00een jur \u0219i cu jeturi puternice alimentate de c\u0103derea materiei de pe disc.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Se ajunge apoi destul de repede \u00een faza de protostea, cu apari\u021bia unui disc proto-planetar \u0219i cu jeturi din ce \u00een ce mai slabe. Ultima faz\u0103 \u00eenaintea na\u0219terii propriu-zise a stelei, se cheam\u0103 faza pre-secven\u021b\u0103 principal\u0103, moment \u00een care jeturile dispar, r\u0103m\u00e2ne un disc de resturi, \u0219i din momentul \u00een care fuziunea nuclear\u0103 e declan\u0219at\u0103, ia na\u0219tere steaua. Toate etapele astea se \u00eent\u00e2mpl\u0103 \u00een c\u00e2teva milioane de ani.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><strong><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Scenariul standard formare planete telurice <\/span><\/span><\/span><\/strong><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Totul porne\u0219te dup\u0103 formarea discului protoplanetar, din moment ce acesta \u00eencepe s\u0103 se r\u0103ceasc\u0103 treptat, pe m\u0103sur\u0103 ce temperatura scade tot mai multe elemente \u00eencep\u00e2nd s\u0103 se condenseze (la mai pu\u021bin de 1600 K &#8211; oxizi de metal, la 1400 K &#8211; fierul, la 1300 K \u2013 silica\u021bii). Ini\u021bial se formeaz\u0103 granule foarte mici, de ordinul c\u00e2torva microni, care \u00eencep apoi s\u0103 creasc\u0103 \u00een m\u0103rime prin ciocniri reciproce, c\u00e2nd viteza de impact este suficient de mic\u0103 pentru ca acestea s\u0103 r\u0103m\u00e2n\u0103 unite, p\u00e2n\u0103 ajung la dimensiuni de c\u00e2\u021biva cm.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2901 aligncenter\" src=\"https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-7.jpg\" alt=\"\" width=\"669\" height=\"441\" srcset=\"https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-7.jpg 1019w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-7-300x198.jpg 300w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-7-768x506.jpg 768w\" sizes=\"auto, (max-width: 669px) 100vw, 669px\" \/><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">C\u00e2nd corpurile solide au ajuns la c\u00e2\u021biva centimetri sau decimetri, modelele de cre\u0219tere prin ciocniri reciproce \u00eent\u00e2mpin\u0103 o problem\u0103 major\u0103 cunoscut\u0103 sub numele de \u201ebariera metrului\u201d. Aceste corpuri se decupleaz\u0103 de gazul din disc, ceea ce face ca vitezele lor relative s\u0103 devin\u0103 mai mari, drept urmare \u00een loc de acumulare are loc eroziune. Una din teoriile \u00eenaintate pentru a explica cum s-ar putea dep\u0103\u0219i bariera metrului se bazeaz\u0103 pe faptul c\u0103 ar exista o dispersie foarte mare \u00een dimensiunea corpurilor solide, astfel c\u0103 cele mai mari dintre aceste corpuri le-ar putea acumula pe cele mai mici, chiar \u0219i la viteze relativ mari.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Se ajunge p\u00e2n\u0103 la urm\u0103 la corpuri solide de ordinul unui kilometru, corpuri denumite \u201eplanetezimale\u201d, care cresc la r\u00e2ndul lor tot prin ciocniri, dar procesul de acre\u021bie de data asta este determinat de gravita\u021bie, \u201elipirea\u201d av\u00e2nd loc c\u00e2nd viteza de coliziune este mai mic\u0103 dec\u00e2t viteza de eliberare a celor dou\u0103 corpuri (pentru corpuri de ordinul unui kilometru, viteza e de ordinul a c\u00e2\u021biva m\/s). Dac\u0103 toate planetezimalele ar fi de aceea\u0219i dimensiune \u0219i ar cre\u0219te \u00eempreun\u0103, atunci ar dura aproximativ 1 milion de ani pentru a forma un corp de 1.000 km \u00eentr-o zon\u0103 aflat\u0103 la aproximativ o unitate astronomic\u0103 de Soare.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Totu\u0219i, procesul e mai rapid pentru c\u0103 unele planetezimale sunt mai mari dec\u00e2t altele \u0219i tind astfel s\u0103 devieze alte corpuri c\u0103tre ele. Ele vor cre\u0219te astfel mai repede \u0219i vor devia \u0219i mai multe planetezimalele mai mici spre ele, exist\u00e2nd astfel un efect \u201ebulg\u0103re de z\u0103pad\u0103\u201d, ajung\u00e2ndu-se la corpuri mai mari \u00een perioade de ordinul a 10<\/span><\/span><\/span><sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">4<\/span><\/span><\/span><\/sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> ani.<\/span><\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">C\u00e2nd embrionii planetari ajung la c\u00e2teva sute de kilometri diametru se intr\u0103 \u00een faza oligarhic\u0103 de acre\u021bie care dureaz\u0103 undeva \u00een jurul a 10<\/span><\/span><\/span><sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">5<\/span><\/span><\/span><\/sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> ani, perioad\u0103 \u00een care obiectele ajung la dimensiuni situate \u00eentre 1.000 \u0219i 3.000 de km. Fiecare embrion creeaz\u0103 treptat \u201evid\u201d \u00een jurul s\u0103u, acumuleaz\u0103 alte planetezimale situate \u00een \u201ezona de hr\u0103nire\u201d, asta p\u00e2n\u0103 c\u00e2nd materia se epuizeaz\u0103. <\/span><\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">\u00cen acest moment, ace\u0219ti embrioni sunt suficient de masivi pentru a se perturba reciproc de la distan\u021b\u0103, perturb\u0103rile duc\u00e2nd la \u00eencruci\u0219area orbitelor \u0219i la ciocniri la viteze mari (chiar dac\u0103 vitezele sunt mari, embrionii sunt destul de masivi pentru ca acumularea s\u0103 fie posibil\u0103). \u201eJocul de bowling\u201d \u00eentre aceste obiecte va dura c\u00e2teva milioane sau chiar c\u00e2teva zeci de milioane de ani, p\u00e2n\u0103 la formarea planetelor.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><strong><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Scenariul standard formare planete gazoase<\/span><\/span><\/span><\/strong><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Formarea planetelor gigantice prezint\u0103 unele constr\u00e2ngeri specifice, una dintre ele fiind faptul c\u0103 trebuie adunat\u0103 foarte mult\u0103 materie dar \u0219i o cantitate enorm\u0103 de gaz, cantitate care trebuie finalizat\u0103 \u00eenainte de dispersarea discului de gaz primordial, adic\u0103 \u00eenainte de maximum 10 milioane de ani. \u00cen scenariul la care ader\u0103 majoritatea cercet\u0103torilor, formarea gigan\u021bilor ar urma un proces care seam\u0103n\u0103 foarte mult cu cel pentru planetele terestre. Diferen\u021ba esen\u021bial\u0103 este c\u0103 suntem dincolo de limita ghe\u021bii \u0219i, prin urmare, particulele solide care vor constitui c\u0103r\u0103mizile form\u0103rii planetare sunt compuse din roci \u0219i ghea\u021b\u0103. Se estimeaz\u0103 c\u0103 acest aspect \u00eenmul\u021be\u0219te cu 4 cantitatea de materie solid\u0103 disponibil\u0103.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2902 aligncenter\" src=\"https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-6.jpg\" alt=\"\" width=\"663\" height=\"390\" srcset=\"https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-6.jpg 1643w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-6-300x177.jpg 300w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-6-1024x603.jpg 1024w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-6-768x452.jpg 768w, https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-6-1536x904.jpg 1536w\" sizes=\"auto, (max-width: 663px) 100vw, 663px\" \/><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Planetezimalele vor fi, prin urmare, mai mari \u0219i vor putea forma embrioni planetari mai masivi. Acest lucru va ajuta, de asemenea, la accelerarea procesului de acumulare \u0219i va compensa faptul c\u0103 vitezele orbitale (\u0219i, prin urmare, \u00eent\u00e2lnirile apropiate) sunt mai mici \u00een regiunile exterioare.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Dac\u0103 masa embrionilor dep\u0103\u0219e\u0219te aproximativ 10 mase terestre, atunci for\u021ba gravita\u021bional\u0103 a proto-planetei este suficient\u0103 pentru a \u00eencepe acumularea de gaz \u00een jurul acesteia. Aceast\u0103 acumulare de gaz este \u00een primul r\u00e2nd progresiv\u0103: se formeaz\u0103 o atmosfer\u0103 dens\u0103 a c\u0103rei mas\u0103 cre\u0219te liniar cu timpul. C\u00e2nd masa de gaz devine comparabil\u0103 cu cea a miezului solid din centru, aceast\u0103 atmosfer\u0103 devine instabil\u0103 \u0219i se pr\u0103bu\u0219e\u0219te. Acumularea gazului se accelereaz\u0103 apoi extrem de rapid \u0219i permite acumularea c\u00e2torva zeci de mase terestre \u00een doar c\u00e2teva mii de ani.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Cele 3 etape ale acestui proces au durate foarte diferite: faza ini\u021bial\u0103 de acumulare oligarhic\u0103 a miezului solid dureaz\u0103 10<\/span><\/span><\/span><sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">5<\/span><\/span><\/span><\/sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> ani, acumularea progresiv\u0103 a \u00eenveli\u0219ului de gaz are loc pe parcursul a c\u00e2teva milioane de ani, \u00een timp ce faza final\u0103 de colaps \u0219i acumulare brutal\u0103 a gazului are loc \u00een c\u00e2teva mii de ani.<\/span><\/span><\/span><\/span><\/p>\n<p align=\"left\"><strong><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Migrarea planetelor<\/span><\/span><\/span><\/strong><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Se \u0219tie \u00eenc\u0103 din anii 1970 c\u0103 o planet\u0103 scufundat\u0103 \u00eentr-un disc de gaz interac\u021bioneaz\u0103 dinamic cu el \u0219i c\u0103 aceast\u0103 interac\u021biune poate fi suficient\u0103 pentru a determina \u00een mod semnificativ planeta s\u0103 migreze. Acest mecanism a fost ini\u021bial \u00een mare m\u0103sur\u0103 ignorat \u00een modelele de formare planetar\u0103, p\u00e2n\u0103 c\u00e2nd au fost descoperite exoplanete, \u00een special \u201eJupiteri fierbin\u021bi\u201d foarte masivi, foarte aproape de steaua lor, planete imposibil de format cu modelul standard.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Se disting 2 mecanisme de migrare foarte distincte. Primul tip are loc c\u00e2nd o protoplanet\u0103 atinge o mas\u0103 comparabil\u0103 cu cea a P\u0103m\u00e2ntului \u00een timp ce discul de gaz este \u00eenc\u0103 prezent, gaz care \u00eencepe s\u0103 interac\u021bioneze dinamic cu ea (planeta interac\u021bioneaz\u0103 cu undele de densitate pe care le creeaz\u0103). Se pierde moment unghiular \u0219i planeta migreaz\u0103 spre interior. Acest mecanism are o singur\u0103 problem\u0103: este prea eficient, migrarea se realizeaz\u0103 \u00een doar 10<\/span><\/span><\/span><sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">4<\/span><\/span><\/span><\/sup><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\"> ani!<\/span><\/span><\/span><\/span><\/p>\n<p align=\"left\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-2903 aligncenter\" src=\"https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-2.gif\" alt=\"\" width=\"514\" height=\"499\" \/><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Migrarea de tip 2 are loc \u00een cazul protoplanetelor mai mari de 10 mase terestre. Aceste obiecte vor s\u0103pa o brazd\u0103 \u00een discul de gaz \u0219i vor goli regiunea din jurul lor, astfel c\u0103 evolu\u021bia radial\u0103 a planetei va fi cuplat\u0103 cu cea a discului. Discul va spirala \u00eencet spre stea datorit\u0103 v\u00e2scozit\u0103\u021bii, astfel c\u0103 \u0219i planeta va migra \u00een acela\u0219i ritm (mult mai lent dec\u00e2t migra\u021bia de tipul I). R\u0103m\u00e2ne o singur\u0103 \u00eentrebare. Cum au reu\u0219it totu\u0219i ca planetele gigant s\u0103 se salveze de steaua lor?<\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Dac\u0103 o planet\u0103 migreaz\u0103 \u00eentotdeauna spre interior, dou\u0103 planete \u00eempreun\u0103 pot opri aceast\u0103 migrare sau chiar o pot inversa cu condi\u021bia ca deschiderile s\u0103pate de cele 2 planete s\u0103 se suprapun\u0103 \u0219i ca planeta intern\u0103 s\u0103 fie de 2-4 ori mai mare dec\u00e2t cealalt\u0103. Acesta este probabil ceea ce s-a \u00eent\u00e2mplat cu cuplul Jupiter\/Saturn. De fapt, acest scenariu presupune c\u0103 cele 4 planete gigantice s-au format mai aproape de Soare dec\u00e2t pozi\u021biile lor actuale \u0219i apoi au migrat pe disc. Jupiter ar fi migrat mai \u00eent\u00e2i spre interior p\u00e2n\u0103 la 1,5 UA de la Soare (migra\u021bie de tip II) \u0219i ar fi ejectat majoritatea corpurilor prezente \u00een actuala regiune a Centurii de Asteorizi. Dup\u0103 ce Saturn i s-a al\u0103turat, interac\u021biunile dintre cele dou\u0103 planete gigantice le-au determinat s\u0103 migreze din nou \u00een afar\u0103, un destin pe care \u0219i Uranus \u0219i Neptun \u00eel vor \u00eemp\u0103rt\u0103\u0219i. \u00cen haosul dinamic care a urmat apoi, planetezimalele din regiunile externe au fost injectate \u00een regiunea centurii de asteroizi.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-2904 aligncenter\" src=\"https:\/\/zoobrasov.ro\/planetariu\/wp-content\/uploads\/2025\/11\/formare-SS-1.gif\" alt=\"\" width=\"513\" height=\"498\" \/><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Migra\u021biile de tip I \u0219i II \u00eenceteaz\u0103 dup\u0103 dispersarea discului de gaz. Dar planetele pot continua s\u0103 se mi\u0219te, dar de data aceasta este prin interac\u021biunea cu planetezimalele reziduale neutilizate \u00een acumularea planetar\u0103, planetezimale care pot fi perturbate pe orbite foarte excentrice, pot \u201es\u0103ri\u201d de la o planet\u0103 la alta sau chiar pot fi ejectate din sistem. Un astfel de proces de interac\u021biune planetezimal\/planet\u0103 pare c\u0103 este la originea structurii actuale a sistemului solar exterior. \u00cen special, acest joc de biliard planetar i-ar fi plasat pe Uranus \u0219i Neptun \u00een pozi\u021bia lor actual\u0103 la 20 \u0219i 30 u.a. de Soare, \u00een timp ce aceste planete s-au format, f\u0103r\u0103 \u00eendoial\u0103, mult mai aproape de stea.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><span style=\"font-family: Calibri, sans-serif; color: #000000;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Se cunoa\u0219te faptul c\u0103 Jupiter \u0219i Saturn s-au format repede, venind apoi r\u00e2ndul gigan\u021bilor de ghea\u021b\u0103 Uranus \u0219i Neptun, cele dou\u0103 corpuri \u00eenghe\u021bate suferind \u00een acela\u0219i timp, cel mai probabil, \u0219i coliziuni cu corpuri mari care au dus la modificarea orient\u0103rii axei lor de rota\u021bie.<\/span><\/span><\/span><\/p>\n<p align=\"left\"><strong><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Modelul de la Nisa<\/span><\/span><\/span><\/span><\/strong><\/p>\n<p align=\"left\"><span style=\"color: #000000;\"><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">Ultimul model <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">de formare a Sistemului Solar <\/span><\/span><\/span><span style=\"font-family: Calibri, sans-serif;\"><span style=\"font-size: large;\"><span lang=\"ro-RO\">acceptat \u00een acest moment este Modelul de la Nisa, dezvoltat de Observatorul de pe Coasta de Azur, Fran\u021ba, model care presupune migra\u021bia planetelor gigant \u0219i care explic\u0103 bombardamentul masiv t\u00e2rziu, formarea Norului lui Oort, existen\u021ba Centurii lui Kuiper, asteroizii troieni etc.<\/span><\/span><\/span><\/span><\/p>\n<p style=\"text-align: right;\" align=\"left\"><em>Imagini: Observatoire de Paris, Universite Paris Science&amp;Lettres<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Scenariul \u201estandard\u201d al form\u0103rii planetare presupune faptul c\u0103 acestea se formeaz\u0103 treptat, pas cu pas, urm\u00e2nd o succesiune de procese distincte. Modelul a fost dezvoltat \u00een anii 1960 &#8211; 1970, pe baza ideilor fizicianului rus Victor Safronov. \u00cen Sistemul Solar avem 8 planete \u0219i toate cele 8 planete orbiteaz\u0103 aproximativ \u00een acela\u0219i plan \u0219i, \u00een [&#8230;]\n","protected":false},"author":3,"featured_media":2899,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[53,4],"tags":[70,56,120,38,159,39,40],"class_list":["post-2897","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-sistemul-solar","tag-astronomie","tag-blog","tag-formare","tag-planete","tag-planetologie","tag-sistem-solar","tag-soare"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/posts\/2897","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/comments?post=2897"}],"version-history":[{"count":2,"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/posts\/2897\/revisions"}],"predecessor-version":[{"id":2905,"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/posts\/2897\/revisions\/2905"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/media\/2899"}],"wp:attachment":[{"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/media?parent=2897"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/categories?post=2897"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zoobrasov.ro\/planetariu\/wp-json\/wp\/v2\/tags?post=2897"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}