Astrofisika: Perbedaan antara revisi

Astronomi adalah ilmu kuno, lama terpisah dari studi fisika [[terestrial]]. Dalam pandangan dunia [[Aristoteles]], benda-benda di langit tampak seperti bola yang tidak berubah dan gerakan satu-satunya adalah gerakan seragam dalam lingkaran. Sementara itu, dunia teresterial adalah alam yang mengalami pertumbuhan dan pembusukan, dan gerakannya berada dalam garis lurus yang berakhir ketika benda tersebut mencapai tujuannya. Terdapat anggapan bahwa luar angkasa terbuat dari jenis materi yang berbeda dari materi yang ditemukan di dunia terestrial; diyakini oleh Aristoteles sebagai [[Aether (elemen klasik)|Aether]],<ref>{{Cite book|last=Lloyd|first=G. E. R. (Geoffrey Ernest Richard)|date=1968|url=http://archive.org/details/aristotlegrowths0000lloy|title=Aristotle : the growth and structure of his thought|location=|publisher=London : Cambridge University Press|isbn=978-0-521-07049-2|pages=134|others=Internet Archive|quote=But the region of the heavenly bodies, from the moon to the outermost circle of the fixed stars, is constituted not by any of these four elements singly or in any combination, but by a fifth element, aither, which has the property of moving naturally in a circle.|url-status=live}}</ref> atau sebagai [[Api (unsur klasik)|Api]] oleh [[Plato]].<ref>{{Cite book|last=Plato|first=|last2=Cornford|first2=Francis M.|date=1997|url=https://books.google.co.id/books?id=KQsmLW8v0WwC&lpg=PP1&pg=PA118#v=onepage&q&f=false|title=Plato's Cosmology: The Timaeus of Plato|location=|publisher=Hackett Publishing|isbn=978-0-87220-386-0|pages=118|language=en|url-status=live}}</ref> Selama abad ke-17, filsuf alam seperti [[Galileo Galilei|Galileo]],<ref>{{Cite book|last=Galilei|first=Galileo|date=1610|url=http://people.reed.edu/~wieting/mathematics537/SideriusNuncius.pdf|title=Sidereus Nuncius|location=Venice|publisher=|isbn=|pages=13|translator-last=Helden|translator-first=Albert Van|trans-title=Sidereal Messenger|quote=By oft-repeated observations of them we have been led to the conclusion that we certainly see the surface of the Moon to be not smooth, even, and perfectly spherical, as the great crowd of philosophers have believed about this and other heavenly bodies, but, on the contrary, to be uneven, rough, and crowded with depressions and bulges. And it is like the face of the Earth itself, which is marked here and there with chains of mountains and depths of valleys.|author-link=Galileo Galilei|url-status=live|access-date=2020-10-31|archive-date=2021-05-13|archive-url=https://web.archive.org/web/20210513224028/https://people.reed.edu/~wieting/mathematics537/SideriusNuncius.pdf|dead-url=yes}}</ref> [[René Descartes|Descartes]],<ref>Slowik, Edward (2017). Zalta, Edward N., ed. ''[https://plato.stanford.edu/entries/descartes-physics/ The Stanford Encyclopedia of Philosophy]'' (Fall 2017 Edition). Metaphysics Research Lab, Stanford University. "It is obvious that when God first created the world, He not only moved its parts in various ways, but also simultaneously caused some of the parts to push others and to transfer their motion to these others. So in now maintaining the world by the same action and with the same laws with which He created it, He conserves motion; not always contained in the same parts of matter, but transferred from some parts to others depending on the ways in which they come in contact."</ref> dan Newton<ref>{{Cite book|last=Bricker|first=Phillip|last2=Hughes|first2=Professor of Philosophy R. I. G.|last3=Hughes|first3=R. I. G.|last4=Hughes|first4=R. I.|date=1990|url=https://books.google.co.id/books?id=oKaQkyCp1toC&lpg=PP1&pg=PA140#v=onepage&q&f=false|title=Philosophical Perspectives on Newtonian Science|location=|publisher=MIT Press|isbn=978-0-262-02301-6|pages=140|language=en|url-status=live}}</ref> mulai berpendapat bahwa daerah angkasa dan terestrial terbuat dari jenis bahan yang serupa dan tunduk pada hukum alam yang sama. Tantangan mereka adalah saat itu belum ditemukan alat untuk membuktikan pernyataan ini.

 

 

Pada tahun 1868, [[Norman Lockyer]] mempelajari garis-garis terang dan gelap dalam spektrum Matahari. Dia bekerja dengan ahli kimia [[Edward Frankland]] untuk menyelidiki spektrum unsur-unsur pada berbagai suhu dan tekanan tetapi tidak dapat menghubungkan garis kuning dalam spektrum Matahari dengan unsur-unsur yang telah diketahui saat itu.<ref>{{Cite journal|last=Cortie|first=A. L.|date=1921-05-01|title=Sir Norman Lockyer, 1836-1920|url=http://adsabs.harvard.edu/abs/1921ApJ....53..233C|journal=The Astrophysical Journal|volume=53|issue=|pages=237|doi=10.1086/142602}}</ref> Dia kemudian menyatakan garis tersebut mewakili elemen baru, disebut [[helium]], dari [[bahasa Yunani]] [[Helios]], dewa Matahari.<ref>{{Cite journal|last=Jensen|first=William B.|date=2004-07-01|title=Why Helium Ends in "-ium"|url=https://doi.org/10.1021/ed081p944|journal=Journal of Chemical Education|volume=81|issue=7|pages=944|doi=10.1021/ed081p944|issn=0021-9584|quote=As a result, Lockyer concluded that it belonged to a unknown element for which the name “helium” (from the Greek, helios, meaning “sun”) was contrived.}}</ref>