{"id":31888,"date":"2019-01-21T01:14:46","date_gmt":"2019-01-20T22:14:46","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=31888"},"modified":"2019-01-20T23:08:34","modified_gmt":"2019-01-20T20:08:34","slug":"dunya-ve-ayin-krater-kardesligi","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2019\/01\/21\/dunya-ve-ayin-krater-kardesligi","title":{"rendered":"D\u00fcnya ve Ay\u2019\u0131n krater karde\u015fli\u011fi"},"content":{"rendered":"

D\u00fcnyam\u0131z\u0131 delik de\u015fik eden g\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131n\u0131n izlerini uzaklarda aramaya gerek yok. Sadece 385 bin kilometre kadar \u00f6temizde bize kozmik tarihimizin kayd\u0131n\u0131 sunan \u00e7ok iyi bir kaynak var: Ay. Toronto \u00dcniversitesi\u2019nden ara\u015ft\u0131rmac\u0131lar da b\u00f6yle d\u00fc\u015f\u00fcnm\u00fc\u015f olacaklar ki NASA\u2019n\u0131n faaliyete soktu\u011fu yeni bir Ay izleme uydusunu kullanarak tam da bu y\u00f6nteme ba\u015fvurdular. Ula\u015ft\u0131klar\u0131 veriler D\u00fcnya\u2019n\u0131n antik tarihini ba\u015ftan yazacak gibi g\u00f6r\u00fcn\u00fcyor! Neden mi?
\nD\u00fcnya\u2019ya \u00e7arpan ve geride krater b\u0131rakan g\u00f6kta\u015flar\u0131ndan 290 milyon y\u0131l \u00f6ncesiyle 650 milyon y\u0131l \u00f6ncesi aral\u0131\u011f\u0131na denk gelenlerin olduk\u00e7a nadir g\u00f6r\u00fclmesi; bu uzak ge\u00e7mi\u015fe ait kraterlerin, ba\u015fta erozyon olmak \u00fczere \u00e7e\u015fitli jeolojik s\u00fcre\u00e7lerin topra\u011f\u0131 a\u015f\u0131nd\u0131r\u0131c\u0131 etkisiyle g\u00f6zden kaybolmas\u0131na ba\u011flan\u0131yordu. Oysa Toronto \u00dcniversitesi Yer Bilimleri B\u00f6l\u00fcm\u00fc\u2019nde doktoras\u0131n\u0131 hen\u00fcz tamamlam\u0131\u015f olan Sara Mazrouei ve ayn\u0131 b\u00f6l\u00fcm\u00fcn \u00f6\u011fretim \u00fcyelerinden Rebecca Ghent\u2019in verileri \u00f6yle s\u00f6ylemiyor. \u0130kilinin \u00e7al\u0131\u015fmas\u0131 D\u00fcnya ve Ay\u2019\u0131 etkileyen g\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131n\u0131n say\u0131s\u0131n\u0131n yakla\u015f\u0131k 290 milyon y\u0131l \u00f6ncesinden itibaren 2,6 kat art\u0131\u015f g\u00f6sterdi\u011fini, D\u00fcnya \u00fczerinde 290 milyon y\u0131ldan eski kraterlerin nadir olmas\u0131n\u0131n ise jeolojik a\u015f\u0131nd\u0131rmadan de\u011fil, bu d\u00f6nemdeki \u00e7arpmalar\u0131n oransal azl\u0131\u011f\u0131ndan kaynakland\u0131\u011f\u0131n\u0131 g\u00f6steriyor. Peki b\u00fct\u00fcn bunlar ne demek ve neden \u00f6nemli?<\/p>\n

\"\"
Ay, D\u00fcnya\u2019dan farkl\u0131 olarak, kraterleri zamanla a\u015f\u0131nd\u0131ran levha tektoni\u011fi etkisinden muaf. Resimde \u00e7al\u0131\u015fmaya dahil edilen Ay kraterleri ve birbirlerine orant\u0131land\u0131r\u0131lm\u0131\u015f kesitleri g\u00f6r\u00fcl\u00fcyor. Kaynak: NASA GSFC\/LRO\/USGS; Alex Parker.<\/figcaption><\/figure>\n

Asl\u0131nda hikaye NASA\u2019n\u0131n 2009\u2019da f\u0131rlatt\u0131\u011f\u0131 Lunar Reconaissance Orbiter (LRO) isimli y\u00fczey izleme cihaz\u0131n\u0131n marifetlerinde kitleniyor. LRO\u2019nun \u00f6zelliklerinden biri, 1 milyar y\u0131ldan gen\u00e7 ve \u00e7ap\u0131 10 km\u2019den b\u00fcy\u00fck t\u00fcm y\u00fczey kraterlerinin haritas\u0131n\u0131 \u00e7\u0131karmak. Bunu yaparken arac\u0131n ilgili komponenti (Diviner denen bir radyometre) Ay\u2019\u0131n y\u00fczeyinden yay\u0131lan \u0131s\u0131y\u0131 \u00f6l\u00e7erek gen\u00e7 kraterlerin a\u015f\u0131nma ya\u015f\u0131n\u0131 belirliyor. Ay gecesinde iri ta\u015flar ince taneli toprak\/kaya par\u00e7alar\u0131na g\u00f6re daha fazla \u0131s\u0131 yay\u0131yor. Bu da termal resimlerde iri par\u00e7alar\u0131n ince taneli olanlardan ay\u0131rt edilmesini sa\u011fl\u0131yor. Bu bilgiden yola \u00e7\u0131kan ara\u015ft\u0131rmac\u0131lar g\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131 s\u0131ras\u0131nda y\u00fczeye yay\u0131lm\u0131\u015f ve akabinde, onmilyonlarca y\u0131l s\u00fcren meteor ya\u011fmurlar\u0131yla k\u0131r\u0131l\u0131p kraterin k\u0131y\u0131lar\u0131na da\u011f\u0131lm\u0131\u015f kaya par\u00e7alar\u0131n\u0131 belirleyip tarihlendirebilmi\u015fler. B\u00f6ylece ne zaman olu\u015ftu\u011fu bilinmeyen ay kraterlerinin ger\u00e7ek ya\u015f\u0131 ortaya \u00e7\u0131km\u0131\u015f. \u0130kinci ve en \u00f6nemli a\u015famada da bunlar\u0131 D\u00fcnya\u2019daki kraterlerin ya\u015f\u0131yla kar\u015f\u0131la\u015ft\u0131r\u0131nca her iki grubun ayn\u0131 g\u00f6kta\u015f\u0131 bombard\u0131man\u0131 \u00f6yk\u00fcs\u00fcn\u00fcn neticesinde olu\u015ftu\u011fu tespit edilmi\u015f. S\u00f6z\u00fcn \u00f6z\u00fc 290 milyon y\u0131l kadar \u00f6nce uzayda bir\u015feyler de\u011fi\u015fmi\u015f ve Ay ile D\u00fcnya kendilerini ayn\u0131 g\u00f6kta\u015f\u0131 ya\u011fmurunun etkisi alt\u0131nda bulmu\u015f. Peki de\u011fi\u015fen ne olmu\u015f?
\nAsl\u0131nda tam bilinmiyor, fakat ara\u015ft\u0131rmac\u0131lar\u0131n dile getirdi\u011fi en akla yatk\u0131n olas\u0131l\u0131\u011f\u0131 iletelim: Mars ve J\u00fcpiter\u2019in y\u00f6r\u00fcngeleri aras\u0131ndaki g\u00f6kta\u015f\u0131 ku\u015fa\u011f\u0131nda, 300 milyon y\u0131ldan uzun bir s\u00fcre \u00f6nce b\u00fcy\u00fck \u00e7arp\u0131\u015fmalar\u0131n meydana geldi\u011fi biliniyor. G\u00fcne\u015f sisteminin i\u00e7 k\u0131s\u0131mlar\u0131na ula\u015f\u0131p D\u00fcnya ve Ay\u2019\u0131 bombalayan g\u00f6kta\u015flar\u0131 da i\u015fte bu \u00e7arp\u0131\u015fmalardan f\u0131rlayan enkazlar olabilir.<\/p>\n

D\u00f6n\u00fcp dola\u015f\u0131p dinozorlara geliyoruz
\n<\/strong>\u00c7al\u0131\u015fmalar\u0131n\u0131n sonu\u00e7lar\u0131n\u0131 Science<\/em> dergisinin 18 Ocak say\u0131s\u0131nda yay\u0131mlayan ekip g\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131n\u0131n dalgalanma g\u00f6sterdi\u011fini ilk s\u00f6yleyenler de\u011fil, fakat bunu istatistiksel olarak g\u00f6sterebilen ve rakamlara d\u00f6ken ilk ekip. \u00c7al\u0131\u015fmay\u0131 \u00f6nemli k\u0131lan bir unsur daha var: G\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131n\u0131n D\u00fcnya \u00fczerindeki canl\u0131l\u0131\u011f\u0131n tarihiyle ili\u015fkisi. D\u00fcnya ve Ay\u2019\u0131 hedef alan g\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131n\u0131n yo\u011funla\u015ft\u0131\u011f\u0131 d\u00f6nem, jeolojik devirlerin diliyle, Paleozoik D\u00f6nem\u2019in sonuna, yani dinozorlardan memelilere kadar bilinen t\u00fcrlerin ye\u015ferdi\u011fi d\u00f6nemin ba\u015flang\u0131c\u0131na kar\u015f\u0131l\u0131k geliyor. Fakat\u00a0 yakla\u015f\u0131k 300 milyon y\u0131ll\u0131k bu evrenin ayn\u0131 zamanda kitlesel yokolu\u015flarla pek \u00e7ok kere kesintiye u\u011frad\u0131\u011f\u0131n\u0131, ard\u0131ndan s\u00f6z konusu felaket d\u00f6nemlerini yeni t\u00fcrlerin h\u0131zla evrimle\u015fmesinin izledi\u011fini de fosil kay\u0131tlar\u0131ndan biliyoruz. Elbette bu ini\u015f \u00e7\u0131k\u0131\u015fl\u0131 s\u00fcre\u00e7ler de\u011fi\u015fik yer ve iklim olaylar\u0131yla ili\u015fkili olabilir. Fakat g\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131 da bunlardan ba\u011f\u0131ms\u0131z d\u00fc\u015f\u00fcn\u00fclebilecek bir olgu de\u011fil. Nitekim \u00e7arpmalar\u0131n yo\u011funla\u015ft\u0131\u011f\u0131 s\u00f6ylenen d\u00f6nemde ya\u015fand\u0131\u011f\u0131 kabul edilen Permiyen sonu yokolu\u015fu (250 milyon y\u0131l \u00f6nce), bilinen kitlesel yokolu\u015flar\u0131n en \u015fiddetlisiydi ve canl\u0131l\u0131\u011f\u0131n %95\u2019ten fazlas\u0131n\u0131 yery\u00fcz\u00fcnden silmi\u015fti. Bunu Triasik sonu yokolu\u015fu (200 milyon y\u0131l \u00f6nces) ile dinozor \u00e7a\u011f\u0131n\u0131 kapat\u0131p k\u00fc\u00e7\u00fck memelilere kap\u0131 aralayan Kretase sonu yokolu\u015fu (66 milyon y\u0131l \u00f6nce) izledi. Dolay\u0131s\u0131yla Rebecca Ghent\u2019in sordu\u011fu soruyu biz de burada tekrarlayabiliriz: \u201cG\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131ndaki hesaplanan s\u0131kla\u015fma ile D\u00fcnya \u00fczerinde uzun s\u00fcre \u00f6nce ya\u015fanm\u0131\u015f olaylar aras\u0131nda do\u011frudan ba\u011flant\u0131 kurulabilir mi?\u201d Bu da ba\u015fka ara\u015ft\u0131rmalar\u0131n konusu olacak.<\/p>\n

Kaynaklar:<\/strong><\/p>\n

1) University of Toronto News, \u201cTeam of scientists led by U of T identify period of increased asteroid impacts on ancient Earth by studying the moon\u201d, 17 Ocak 2019.<\/p>\n

2) University of Southampton News, \u201cEarth and Moon pummelled by more asteroids since the age of the dinosaurs began\u201d, 17 Ocak 2019.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

D\u00fcnyam\u0131z\u0131 delik de\u015fik eden g\u00f6kta\u015f\u0131 \u00e7arpmalar\u0131n\u0131n izlerini uzaklarda aramaya gerek yok. Sadece 385 bin kilometre kadar \u00f6temizde bize kozmik tarihimizin kayd\u0131n\u0131 sunan \u00e7ok iyi bir kaynak var: Ay. Toronto \u00dcniversitesi\u2019nden ara\u015ft\u0131rmac\u0131lar da b\u00f6yle d\u00fc\u015f\u00fcnm\u00fc\u015f olacaklar ki NASA\u2019n\u0131n faaliyete soktu\u011fu yeni bir Ay izleme uydusunu kullanarak tam da bu y\u00f6nteme ba\u015fvurdular. Ula\u015ft\u0131klar\u0131 veriler D\u00fcnya\u2019n\u0131n antik tarihini […]<\/p>\n","protected":false},"author":184,"featured_media":31897,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"video","meta":{"_acf_changed":false,"footnotes":""},"categories":[30,19,232],"tags":[787,4452,4454,4453],"class_list":["post-31888","post","type-post","status-publish","format-video","has-post-thumbnail","hentry","category-astronomi","category-bilim-gundemi","category-yerbilimleri","tag-ay","tag-goktasi-carpmasi","tag-kitlesel-yokoluslar","tag-krater","post_format-post-format-video"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t