{"id":13126,"date":"2020-08-30T12:48:13","date_gmt":"2020-08-30T12:48:13","guid":{"rendered":"http:\/\/uni.hi.is\/einar\/?p=13126"},"modified":"2020-08-30T12:48:13","modified_gmt":"2020-08-30T12:48:13","slug":"stjarnedlisfraedi-og-heimsfraedi-a-islandi-2-timabilid-1780-1870-b-stjarnedlisfraedi-fyrir-daga-newtons","status":"publish","type":"post","link":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/?p=13126","title":{"rendered":"Stjarne\u00f0lisfr\u00e6\u00f0i og heimsfr\u00e6\u00f0i \u00e1 \u00cdslandi 2: T\u00edmabili\u00f0 1780-1870  (b) Stjarne\u00f0lisfr\u00e6\u00f0i fyrir daga Newtons"},"content":{"rendered":"<p style=\"text-align: right\"><a href=\"https:\/\/uni.hi.is\/einar\/2021\/05\/02\/greinaflokkur-um-stjarnedlisfraedi-og-heimsfraedi-a-islandi\/\">Yfirlit um greinaflokkinn<\/a><\/p>\n<p>Margir sagnfr\u00e6\u00f0ingar vilja rekja upphaf n\u00fat\u00edma stjarne\u00f0lisfr\u00e6\u00f0i til mi\u00f0biks n\u00edtj\u00e1ndu aldar, \u00feegar n\u00fd t\u00e6kni, bygg\u00f0 \u00e1 e\u00f0lisfr\u00e6\u00f0i og efnafr\u00e6\u00f0i, var tekin \u00ed notkun vi\u00f0 ranns\u00f3knir \u00e1 fyrirb\u00e6rum stj\u00f6rnuhiminsins. H\u00e9r er fyrst og fremst \u00e1tt vi\u00f0 hinar mikilv\u00e6gu <a href=\"https:\/\/history.aip.org\/exhibits\/cosmology\/tools\/tools-spectroscopy.htm\">litr\u00f3fsm\u00e6lingar<\/a>, en jafnframt <a href=\"https:\/\/en.wikipedia.org\/wiki\/Astrophotography\">lj\u00f3smyndat\u00e6knina<\/a>, sem var\u00f0 s\u00edfellt gagnlegri eftir \u00fev\u00ed sem t\u00edmar li\u00f0u. Nafni\u00f0 stjarne\u00f0lisfr\u00e6\u00f0i (\u00fe. Astrophysik) mun og fyrst hafa s\u00e9st \u00e1 prenti \u00e1ri\u00f0 1865 (\u00ed riti \u00fe\u00fdska e\u00f0lisfr\u00e6\u00f0ingsins <a href=\"https:\/\/de.wikipedia.org\/wiki\/Karl_Friedrich_Z%C3%B6llner\">K. F. Z\u00f6lners<\/a> um <a href=\"https:\/\/books.google.is\/books?id=BjIAAAAAQAAJ&amp;source=gbs_navlinks_s\">lj\u00f3sm\u00e6lingar<\/a>). Um \u00feessa byltingarkenndu \u00fer\u00f3un og hvernig vitneskja um hana barst til \u00cdslands ver\u00f0ur fjalla\u00f0 \u00ed n\u00e6sta kafla greinaflokksins <span style=\"color: #00ff00\">(3)<\/span>.<\/p>\n<p>A\u00f0 mati \u00feess, sem \u00feetta ritar, m\u00e1 rekja s\u00f6gu stjarne\u00f0lisfr\u00e6\u00f0innar mun lengra aftur \u00ed t\u00edmann, e\u00f0a sem nemur 250 \u00e1rum; til upphafs \u00feeirrar fr\u00e6\u00f0igreinar, sem vi\u00f0 n\u00fa k\u00f6llum <em>kennilega stjarne\u00f0lisfr\u00e6\u00f0i<\/em> (e. theoretical astrophysics). \u00dea\u00f0 heiti mun a\u00f0 v\u00edsu ekki hafa komi\u00f0 til s\u00f6gunnar fyrr en me\u00f0 verkum <a href=\"https:\/\/en.wikipedia.org\/wiki\/Arthur_Eddington\">A. S. Eddingtons<\/a> og samt\u00edmamanna hans \u00e1 fyrstu \u00e1ratugum tuttugustu aldar og \u00fdmsir sagnfr\u00e6\u00f0ingar vilja \u00fev\u00ed rekja upphaf greinarinnar til \u00feess t\u00edma. En \u00ed hugum flestra stjarne\u00f0lisfr\u00e6\u00f0inga (allavega \u00feeirra, sem hafa haft fyrir \u00fev\u00ed a\u00f0 kynna s\u00e9r s\u00f6guna) voru fyrstu forverarnir upp \u00e1 sitt besta \u00e1 sautj\u00e1ndu \u00f6ld, menn eins og <a href=\"https:\/\/en.wikipedia.org\/wiki\/Johannes_Kepler\">Kepler<\/a>, <a href=\"https:\/\/en.wikipedia.org\/wiki\/Galileo_Galilei\">Gal\u00edle\u00f3<\/a>, <a href=\"https:\/\/en.wikipedia.org\/wiki\/Ren%C3%A9_Descartes\">Descartes<\/a>, <a href=\"https:\/\/en.wikipedia.org\/wiki\/Christiaan_Huygens\">Huygens<\/a> og s\u00ed\u00f0ast en ekki s\u00edst <a href=\"https:\/\/en.wikipedia.org\/wiki\/Isaac_Newton\">Newton<\/a>.<\/p>\n<p>Allir voru \u00feessir frumkv\u00f6\u00f0lar fram\u00farskarandi st\u00e6r\u00f0fr\u00e6\u00f0ilegir l\u00e6rd\u00f3msmenn og n\u00e1tt\u00faruspekingar og jafnframt\u00a0 \u00e1kafir stu\u00f0ningsmenn <a href=\"https:\/\/en.wikipedia.org\/wiki\/Copernican_heliocentrism\">s\u00f3lmi\u00f0jukenningarinnar<\/a>. \u00dea\u00f0 voru \u00feeir, \u00e1samt \u00fdmsum \u00f6\u00f0rum, en kannski ekki jafn \u00feekktum l\u00e6rd\u00f3msm\u00f6nnum fyrri t\u00edma, sem m\u00f3tu\u00f0u grundv\u00f6ll s\u00edgildrar aflfr\u00e6\u00f0i og lj\u00f3sfr\u00e6\u00f0i og beittu \u00feeirri \u00feekkingu sm\u00e1m saman til a\u00f0 \u00f6\u00f0last e\u00f0lisfr\u00e6\u00f0ilegan skilning \u00e1 eiginleikum s\u00f3lkerfisins og gangi himintungla. Yfirlit um \u00feessa merku s\u00f6gu m\u00e1 me\u00f0al annars finna \u00ed eftirfarandi ritsm\u00ed\u00f0um:<\/p>\n<ul>\n<li>A. Berry, 1898: <a href=\"https:\/\/archive.org\/details\/shorthistoryofas025511mbp\/page\/n5\">A Short History of Astronomy<\/a>.<\/li>\n<li>J. L. E. Dreyer, 1906: <a href=\"https:\/\/archive.org\/details\/historyofplaneta00dreyuoft\/page\/n5\/mode\/2up\">History of the planetary systems from Thales to Kepler<\/a>. <a href=\"https:\/\/books.google.is\/books?id=mI0TxowaDVsC&amp;source=gbs_navlinks_s\">Endur\u00fatgefin<\/a> hj\u00e1 Dover 1953.<\/li>\n<li>A. Pannekoek, 1961: <a href=\"https:\/\/books.google.is\/books?id=I1LGdDe0NYcC&amp;source=gbs_navlinks_s\">A History of Astronomy<\/a>.<\/li>\n<li>\u00deorsteinn Vilhj\u00e1lmsson, 1986-87: <a href=\"https:\/\/timarit.is\/page\/6535193?iabr=on#page\/n179\/mode\/2up\">Heimsmynd \u00e1 hverfanda hveli: Sagt fr\u00e1 heimss\u00fdn v\u00edsindanna fr\u00e1 \u00f6ndver\u00f0u fram yfir daga Newtons, I-II<\/a>.<\/li>\n<li>R. Taton &amp; C. Wilson ritstj., 1989: <a href=\"https:\/\/www.cambridge.org\/is\/academic\/subjects\/physics\/history-philosophy-and-foundations-physics\/planetary-astronomy-renaissance-rise-astrophysics-part?format=PB&amp;isbn=9780521542050\">The General History of Astronomy: Planetary Astronomy from the Renaissance to the Rise of Astrophysics &#8211; Part 2A: Tycho Brahe to Newton<\/a>.<\/li>\n<li>Andri S. Bj\u00f6rnsson, 2004: <a href=\"http:\/\/haskolautgafan.hi.is\/visindabyltingin\">V\u00edsindabyltingin og r\u00e6tur hennar \u00ed forn\u00f6ld og \u00e1 mi\u00f0\u00f6ldum<\/a>.<\/li>\n<li>O. Gingerich, 2011: <a href=\"http:\/\/articles.adsabs.harvard.edu\/\/full\/2011IAUS..260..172G\/0000172.000.html\">Kepler, Galileo and the birth of modern astronomy<\/a>.<\/li>\n<li>T. Christie, 2019-20: <a href=\"https:\/\/thonyc.wordpress.com\/the-emergence-of-modern-astronomy-a-complex-mosaic\/\">The emergence of modern astronomy \u2013 a complex mosaic<\/a>.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3 style=\"text-align: center\"><span style=\"font-size: 14pt\"><strong>J\u00f3hannes Kepler<\/strong><\/span><\/h3>\n<figure id=\"attachment_19765\" aria-describedby=\"caption-attachment-19765\" style=\"width: 365px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-19765\" src=\"https:\/\/uni.hi.is\/einar\/files\/2021\/08\/Kepler_Portrait-198x300.jpg\" alt=\"\" width=\"365\" height=\"553\" srcset=\"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2021\/08\/Kepler_Portrait-198x300.jpg 198w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2021\/08\/Kepler_Portrait-677x1024.jpg 677w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2021\/08\/Kepler_Portrait-768x1162.jpg 768w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2021\/08\/Kepler_Portrait-1015x1536.jpg 1015w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2021\/08\/Kepler_Portrait.jpg 1321w\" sizes=\"auto, (max-width: 365px) 100vw, 365px\" \/><figcaption id=\"caption-attachment-19765\" class=\"wp-caption-text\"><span style=\"font-size: 10pt\">Fyrsti stjarne\u00f0lisfr\u00e6\u00f0ingurinn, <a href=\"https:\/\/en.wikipedia.org\/wiki\/Johannes_Kepler\">J\u00f3hannes Kepler<\/a>, \u00e1ri\u00f0 1620.\u00a0 Mynd: Photographische Gesellschaft Berlin. <a href=\"https:\/\/arxiv.org\/abs\/2108.02213\">Sj\u00e1 h\u00e9r<\/a> fr\u00f3\u00f0legan pistil um \u00fdmsar myndir af Kepler.<\/span><\/figcaption><\/figure>\n<p>\u00cd m\u00ednum huga er Kepler tv\u00edm\u00e6lalaust fyrsti eiginlegi stjarne\u00f0lisfr\u00e6\u00f0ingurinn og b\u00f3k hans <a href=\"https:\/\/en.wikipedia.org\/wiki\/Astronomia_nova\">Astronomia Nova<\/a> fyrsta stjarne\u00f0lisfr\u00e6\u00f0iriti\u00f0. \u00deetta mikilv\u00e6gasta verk hans kom \u00fat \u00e1ri\u00f0 1609 og heitir fullu nafni <a href=\"https:\/\/archive.org\/details\/Astronomianovaa00Kepl\/page\/n3\/mode\/2up\">Astronomia Nova \u0391\u0399\u03a4\u0399\u039f\u039b\u039f\u0393\u0397\u03a4\u039f\u03a3, seu physica coelestis<i title=\"Latin language text\">,<\/i> tradita commentariis de motibus stellae Martis ex observationibus G.V. Tychonis Brahe<\/a> (<em>N\u00fd stj\u00f6rnulist, grundv\u00f6llu\u00f0 \u00e1 ors\u00f6kum, e\u00f0a n\u00e1tt\u00faruspeki stj\u00f6rnuheimsins, kynnt me\u00f0 athugasemdum um hreyfingar stj\u00f6rnunnar MARS, bygg\u00f0 \u00e1 m\u00e6lingum a\u00f0alsmannsins T\u00fdch\u00f3s Brahe &#8211; <\/em>Verki\u00f0 er til \u00ed endursko\u00f0a\u00f0ri <a href=\"https:\/\/www.greenlion.com\/books\/astronomianova.html\">enskri \u00fe\u00fd\u00f0ingu<\/a> fr\u00e1 2015).<\/p>\n<p>Yfirl\u00fdst markmi\u00f0 h\u00f6fundarins var a\u00f0 beita n\u00e1tt\u00faruspeki \u00feess t\u00edma til <strong>a\u00f0 \u00fatsk\u00fdra <\/strong>hreyfingar himintunglanna og sj\u00e1lfur titillinn v\u00edsar \u00ed \u00fe\u00e1 fyrir\u00e6tlan: A<em>stronomia nova<\/em> = <em>n\u00fd stj\u00f6rnulist<\/em> = <em>n\u00fd stj\u00f6rnufr\u00e6\u00f0i<\/em>\u00a0 og\u00a0 <em>physica coelestis<\/em> = <em>n\u00e1tt\u00faruspeki stj\u00f6rnuheimsins<\/em> = <em>e\u00f0lisfr\u00e6\u00f0i stj\u00f6rnuheimsins<\/em> (= <em>stjarne\u00f0lisfr\u00e6\u00f0i<\/em>).<\/p>\n<p>Verki\u00f0 byggir me\u00f0al annars \u00e1 s\u00f3lmi\u00f0jukenningu <a href=\"https:\/\/en.wikipedia.org\/wiki\/Nicolaus_Copernicus\">K\u00f3pern\u00edkusar<\/a> og m\u00e6lingum <a href=\"https:\/\/en.wikipedia.org\/wiki\/Tycho_Brahe\">T\u00fdch\u00f3s Brahe<\/a> \u00e1 tilf\u00e6rslu f\u00f6ruhnattanna \u00e1 stj\u00f6rnuhimninum, s\u00e9rstaklega \u00fe\u00f3 \u00edtarlegum m\u00e6lingum hans \u00e1 hreyfingu Mars. \u00dea\u00f0 er \u00ed \u00feessu verki sem Kepler \u201elei\u00f0ir \u00fat\u201c fyrstu tv\u00f6 l\u00f6gm\u00e1l s\u00edn af \u00feremur, sem l\u00fdsa hreyfingum reikistjarnanna umhverfis s\u00f3lina. A\u00f0 auki setur hann fram \u201ee\u00f0lisfr\u00e6\u00f0ilega kenningu\u201c um \u00fea\u00f0, hvernig s\u00f3lin valdi hreyfingu reikistjarnanna, hina fyrstu, sem m\u00e9r er kunnugt um.<\/p>\n<figure id=\"attachment_15791\" aria-describedby=\"caption-attachment-15791\" style=\"width: 442px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-15791\" src=\"https:\/\/uni.hi.is\/einar\/files\/2020\/08\/KopernicusBrahe-300x264.png\" alt=\"\" width=\"442\" height=\"389\" srcset=\"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/08\/KopernicusBrahe-300x264.png 300w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/08\/KopernicusBrahe.png 444w\" sizes=\"auto, (max-width: 442px) 100vw, 442px\" \/><figcaption id=\"caption-attachment-15791\" class=\"wp-caption-text\"><span style=\"font-size: 10pt\">\u00cd verkinu <em>Astronomia nova<\/em> fr\u00e1 1609 studdist Kepler vi\u00f0 s\u00f3lmi\u00f0jukenningu <a href=\"https:\/\/en.wikipedia.org\/wiki\/Nicolaus_Copernicus\">Nikul\u00e1sar K\u00f3pern\u00edkusar<\/a> (til vinstri) og hinar n\u00e1kv\u00e6mu m\u00e6lingar <a href=\"https:\/\/en.wikipedia.org\/wiki\/Tycho_Brahe\">T\u00fdch\u00f3s Brahe<\/a> (til h\u00e6gri). Myndir: Wikipedia.<br \/><\/span><\/figcaption><\/figure>\n<ul>\n<li>O. Gingerich, 1972: <a href=\"http:\/\/articles.adsabs.harvard.edu\/\/full\/1972QJRAS..13..346G\/0000346.000.html\">Johannes Kepler and the New Astronomy<\/a>.<\/li>\n<li>B. Stephenson, 1987: <a href=\"https:\/\/books.google.is\/books?id=EpDTBwAAQBAJ&amp;hl=is&amp;source=gbs_navlinks_s\">Kepler&#8217;s Physical Astronomy.<\/a><\/li>\n<li>G. Holton, 1956: <a href=\"https:\/\/dash.harvard.edu\/handle\/1\/37902459\">Johannes Kepler&#8217;s Universe: Its Physics and Metaphysics<\/a>.<\/li>\n<li>P. Barker &amp; B. R. Goldstein, 2001: <a href=\"https:\/\/www.jstor.org\/stable\/301981?seq=1#metadata_info_tab_contents\">Theological Foundations of Kepler&#8217;s Astronomy<\/a>.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p style=\"text-align: center\"><span style=\"font-size: 14pt\"><strong>L\u00f6gm\u00e1l Keplers<\/strong><\/span><\/p>\n<p>Flestir n\u00falifandi \u00cdslendingar kannast eflaust vi\u00f0 <a href=\"https:\/\/en.wikipedia.org\/wiki\/Kepler%27s_laws_of_planetary_motion\">l\u00f6gm\u00e1lin \u00ferj\u00fa<\/a>, sem kennd eru vi\u00f0 Kepler. Mikilv\u00e6gara er \u00fe\u00f3, a\u00f0 Newton nota\u00f0i \u00feau sem vegv\u00edsi \u00ed leit sinni a\u00f0 hinu merka l\u00f6gm\u00e1li um \u00feyngdina, sem hann setti fram \u00e1ri\u00f0 1687. Um \u00feyngdarl\u00f6gm\u00e1l Newtons og kynni \u00cdslendinga af \u00fev\u00ed ver\u00f0ur fjalla\u00f0 \u00ed n\u00e6stu f\u00e6rslu, en h\u00e9r ver\u00f0ur r\u00e6tt n\u00e1nar um l\u00f6gm\u00e1l Keplers og \u00fatsk\u00fdringar hans \u00e1 hreyfingum himintungla.<\/p>\n<p>Eins og \u00e1\u00f0ur sag\u00f0i, birti Kepler fyrstu tv\u00f6 l\u00f6gm\u00e1lin \u00ed <em>Astronomia nova<\/em> \u00e1ri\u00f0 1609, en hi\u00f0 \u00feri\u00f0ja kom hins vegar ekki fyrr en t\u00edu \u00e1rum s\u00ed\u00f0ar \u00ed verkinu <a href=\"https:\/\/archive.org\/details\/ioanniskepplerih00kepl\/page\/n9\/mode\/2up\">Harmonices Mundi<\/a> (<em>Samhlj\u00f3mur heimsins;<\/em> <a href=\"https:\/\/books.google.is\/books?id=rEkLAAAAIAAJ&amp;source=gbs_navlinks_s\">ensk \u00fe\u00fd\u00f0ing<\/a>; <a href=\"https:\/\/en.wikipedia.org\/wiki\/Harmonices_Mundi\">umfj\u00f6llun<\/a>). \u00cd b\u00e1\u00f0um tilvikum eru l\u00f6gm\u00e1lin dreif\u00f0 innan um anna\u00f0 efni og ekki s\u00e9rlega a\u00f0gengileg. \u00c1ri\u00f0 1622 setti Kepler \u00feau hins vegar fram \u00e1 a\u00f0eins skipulegri h\u00e1tt \u00ed 4. bindi kennslub\u00f3karinnar <a href=\"https:\/\/archive.org\/details\/bub_gb_FaMM9-9BkkgC\/mode\/1up\">Epitome Astronomiae Copernicanae<\/a> (<em>\u00c1grip af stj\u00f6rnufr\u00e6\u00f0i K\u00f3pern\u00edkusar; <\/em><a href=\"https:\/\/books.google.is\/books\/about\/Epitome_of_Copernican_Astronomy.html?id=t23vAAAAMAAJ&amp;redir_esc=y\">ensk \u00fe\u00fd\u00f0ing<\/a>; <a href=\"https:\/\/en.wikipedia.org\/wiki\/Epitome_Astronomiae_Copernicanae\">umfj\u00f6llun<\/a>), sem \u00ed raun er n\u00e1kv\u00e6m fransetning \u00e1 stj\u00f6rnufr\u00e6\u00f0i Keplers sj\u00e1lfs, frekar en K\u00f3pern\u00edkusar.\u00a0 \u00dea\u00f0 var \u00fe\u00f3 ekki fyrr en me\u00f0 al\u00fe\u00fd\u00f0uriti Frakkans <a href=\"https:\/\/en.wikipedia.org\/wiki\/J%C3%A9r%C3%B4me_Lalande\">J. Lalandes<\/a> fr\u00e1 1774, <a href=\"https:\/\/books.google.is\/books?id=YLIWAAAAQAAJ&amp;source=gbs_navlinks_s\">Abr\u00e9g\u00e9 d&#8217;astronomie<\/a>, sem l\u00f6gm\u00e1l Keplers fengu \u00feau n\u00famer, sem vi\u00f0 \u00feekkjum \u00ed dag.<\/p>\n<figure id=\"attachment_14718\" aria-describedby=\"caption-attachment-14718\" style=\"width: 366px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-14718\" src=\"https:\/\/uni.hi.is\/einar\/files\/2020\/05\/Kepler_1_bls292_Astronomia-nova-266x300.png\" alt=\"\" width=\"366\" height=\"413\" srcset=\"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/Kepler_1_bls292_Astronomia-nova-266x300.png 266w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/Kepler_1_bls292_Astronomia-nova-768x866.png 768w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/Kepler_1_bls292_Astronomia-nova.png 874w\" sizes=\"auto, (max-width: 366px) 100vw, 366px\" \/><figcaption id=\"caption-attachment-14718\" class=\"wp-caption-text\"><span style=\"font-size: 10pt\">Mynd \u00far <em>Astronomia nova<\/em> fr\u00e1 1609 (bls. 286) H\u00fan \u00e1 a\u00f0 s\u00fdna sporbaug reikistj\u00f6rnunnar Mars. \u00dea\u00f0 d\u00e6mi var fyrsta v\u00edsbending Keplers um ni\u00f0urst\u00f6\u00f0u, sem n\u00fa ber nafni\u00f0 <em>fyrsta l\u00f6gm\u00e1l Keplers<\/em>.<\/span><\/figcaption><\/figure>\n<p>\u00cd fyrstu voru l\u00f6gm\u00e1lin l\u00edti\u00f0 notu\u00f0, enda voru verk Keplers erfi\u00f0 aflestrar og st\u00e6r\u00f0fr\u00e6\u00f0in a\u00f0eins a\u00f0gengileg f\u00e1um, s\u00e9rstaklega ef menn vildu <a href=\"https:\/\/en.wikipedia.org\/wiki\/Kepler%27s_laws_of_planetary_motion#Position_as_a_function_of_time\">notast vi\u00f0 anna\u00f0 l\u00f6gm\u00e1li\u00f0<\/a> (meira <a href=\"https:\/\/en.wikipedia.org\/wiki\/Kepler%27s_equation\">h\u00e9r<\/a>). \u00c1ri\u00f0 1627 gaf Kepler hins vegar \u00fat <a href=\"https:\/\/books.google.is\/books?id=lZRcAAAAcAAJ&amp;printsec=frontcover&amp;source=gbs_ge_summary_r&amp;cad=0#v=onepage&amp;q&amp;f=false\">Tabulae Rudolphinae<\/a> (<em>T\u00f6flur R\u00fad\u00f3lfs;<\/em> <a href=\"https:\/\/en.wikipedia.org\/wiki\/Rudolphine_Tables\">umfj\u00f6llun<\/a>), lang\u00fer\u00e1\u00f0ar <a href=\"http:\/\/www.sites.hps.cam.ac.uk\/starry\/tables.html\">stjarnfr\u00e6\u00f0it\u00f6flur<\/a>, bygg\u00f0ar \u00e1 hans eigin l\u00f6gm\u00e1lum og athugunum T\u00fdch\u00f3s Brahe.<\/p>\n<p>Stj\u00f6rnufr\u00e6\u00f0ingar uppg\u00f6tvu\u00f0u flj\u00f3tlega, a\u00f0 <em>T\u00f6flur R\u00fad\u00f3lfs<\/em> voru til muna n\u00e1kv\u00e6mari en allar fyrri t\u00f6flur af svipa\u00f0ri ger\u00f0 og olli \u00fea\u00f0 vaxandi \u00e1huga \u00e1 l\u00f6gm\u00e1lum Keplers. Hins vegar s\u00fdndi Gal\u00edle\u00f3 \u00feeim \u00e1vallt l\u00edtinn sem engan \u00e1huga og hi\u00f0 sama gilti um Descartes og fylgismenn hans. Notkun \u00feeirra var\u00f0 \u00fev\u00ed ekki mj\u00f6g almenn fyrr en Newton s\u00fdndi fram \u00e1 mikilv\u00e6gi \u00feeirra \u00ed <a href=\"https:\/\/en.wikipedia.org\/wiki\/Philosophi%C3%A6_Naturalis_Principia_Mathematica\">Philosophi\u00e6 Naturalis Principia Mathematica<\/a> (<em>St\u00e6r\u00f0fr\u00e6\u00f0il\u00f6gm\u00e1lum n\u00e1tt\u00faruspekinnar<\/em>) \u00e1ri\u00f0 1687.<\/p>\n<p>Af \u00e1st\u00e6\u00f0um, sem komi\u00f0 ver\u00f0ur inn \u00e1 h\u00e9r \u00e1 eftir, notu\u00f0u danskir stj\u00f6rnufr\u00e6\u00f0ingar hvorki <em>T\u00f6flur R\u00fad\u00f3lfs<\/em> n\u00e9 kennslub\u00f3k Keplers, <em>Epitome,<\/em> fyrr en <a href=\"https:\/\/notendur.hi.is\/~einar\/SAGA\/Roemer.pdf\">Ole R\u00f6mer<\/a> var\u00f0 pr\u00f3fessor vi\u00f0 Hafnarh\u00e1sk\u00f3la \u00e1ri\u00f0 1681. Hann nota\u00f0i \u00feessi verk me\u00f0al annars \u00ed kennslunni, eins og sj\u00e1 m\u00e1 af disp\u00fatat\u00edum <a href=\"https:\/\/uni.hi.is\/einar\/2019\/11\/26\/magnus-arason-landmaelingamadur\/\">Magn\u00fasar Arasonar<\/a> og <a href=\"https:\/\/is.wikipedia.org\/wiki\/%C3%9Eorleifur_Halld%C3%B3rsson\">\u00deorleifs Halld\u00f3rssonar<\/a> fr\u00e1 \u00e1runum 1707 til 1710. Keplersl\u00f6gm\u00e1lin ur\u00f0u \u00feannig fastur hluti af n\u00e1msefninu vi\u00f0 H\u00e1sk\u00f3lann \u00e1 n\u00edunda \u00e1ratugi sautj\u00e1ndu aldar \u00e1n nokurra \u00e1hrifa fr\u00e1 Newton, enda \u00e1ttu enn eftir a\u00f0 l\u00ed\u00f0a nokkrir \u00e1ratugir \u00fear til n\u00e1tt\u00faruspeki enska meistarans barst til Kaupmannahafnar.<\/p>\n<p>Fyrstu \u00edtarlegu umfj\u00f6llunina \u00e1 \u00edslensku um \u00f6ll l\u00f6gm\u00e1l Keplers er a\u00f0 finna \u00ed <a href=\"https:\/\/baekur.is\/bok\/000402495\/Stjornufraedi__lett_og_handa\">Stj\u00f6rnufr\u00e6di<\/a> Ursins fr\u00e1 1842 (bls. 76-78).\u00a0 Eins og minnst var \u00e1 \u00ed <a href=\"https:\/\/uni.hi.is\/einar\/2020\/07\/23\/stjarnedlisfraedi-og-heimsfraedi-a-islandi-2a-timabilid-1780-1870-skeid-newtons-skolahald-althydufraedsla-tidarandi\/\">f\u00e6rslu 2a<\/a>, kemur fyrsta l\u00f6gm\u00e1li\u00f0 \u00fe\u00f3 vi\u00f0 s\u00f6gu strax \u00ed fyrstu \u00edslensku al\u00fe\u00fd\u00f0uritunum, b\u00e6\u00f0i \u00ed verkum Magn\u00fasar Stepensen og Hannesar Finnssonar fr\u00e1 \u00e1rinu 1797. Hvorugur \u00feeirra talar \u00fe\u00f3 um ellipsur \u00ed \u00fev\u00ed sambandi, heldur nota or\u00f0alagi\u00f0 \u201eaflangir hringir\u201c um brautirnar (or\u00f0i\u00f0 sporbaugur er eftir J\u00f3nas Hallgr\u00edmsson og kemur fyrst fyrir \u00ed <em>Stj\u00f6rnufr\u00e6\u00f0i<\/em> Ursins). Hi\u00f0 sama gerir J\u00f3n J\u00f3nsson \u00e1ri s\u00ed\u00f0ar \u00ed \u00fe\u00fd\u00f0ingu sinni \u00e1 <a href=\"https:\/\/baekur.is\/bok\/000380271\/0\/5\/Sa_gudlega_thenkjandi_Bls_5\">N\u00e1tt\u00farusko\u00f0ara<\/a> Suhms.<\/p>\n<figure id=\"attachment_15689\" aria-describedby=\"caption-attachment-15689\" style=\"width: 370px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-15689\" src=\"https:\/\/uni.hi.is\/einar\/files\/2020\/07\/Ursin_Kepler-300x281.png\" alt=\"\" width=\"370\" height=\"346\" srcset=\"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/07\/Ursin_Kepler-300x281.png 300w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/07\/Ursin_Kepler-1024x960.png 1024w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/07\/Ursin_Kepler-768x720.png 768w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/07\/Ursin_Kepler.png 1050w\" sizes=\"auto, (max-width: 370px) 100vw, 370px\" \/><figcaption id=\"caption-attachment-15689\" class=\"wp-caption-text\"><span style=\"font-size: 10pt\">Myndin er \u00far <em>Stj\u00f6rnufr\u00e6di<\/em> Ursins og \u00e1 a\u00f0 \u00fatsk\u00fdra fyrstu tv\u00f6 l\u00f6gm\u00e1l Keplers um hreyfingar \u00ed s\u00f3lkerfinu: <strong>1.<\/strong> Braut s\u00e9rhverrar reikistj\u00f6rnu (AGEDBPH) er <a href=\"https:\/\/en.wikipedia.org\/wiki\/Ellipse\">sporbaugur<\/a> me\u00f0 s\u00f3lina (S) \u00ed \u00f6\u00f0rum brennista\u00f0 (brennipunkti) brautarinnar. \u00a0 <strong>2.<\/strong> Tengil\u00edna s\u00e9rhverrar reikistj\u00f6rnu og s\u00f3lar fer yfir jafnst\u00f3r flatarm\u00e1l (skygg\u00f0u sv\u00e6\u00f0in) \u00e1 jafnl\u00f6ngum t\u00edma.\u00a0 &#8211;\u00a0 Af 2. l\u00f6gm\u00e1inu m\u00e1 sj\u00e1, a\u00f0 hra\u00f0i reikistj\u00f6rnu \u00e1 braut sinni er breytilegur, mestur \u00ed s\u00f3ln\u00e1nd P, minnstur \u00ed s\u00f3lfj\u00e6r\u00f0 (s\u00f3lfir\u00f0) A.<br \/><\/span><\/figcaption><\/figure>\n<p style=\"text-align: left\">\u00cd upphafi s\u00fdndu stj\u00f6rnufr\u00e6\u00f0ingar \u00feri\u00f0ja l\u00f6gm\u00e1li Keplers s\u00e9rstaklega l\u00edtinn \u00e1huga. \u00c1st\u00e6\u00f0an var einfaldlega s\u00fa, a\u00f0 \u00fea\u00f0 kom a\u00f0 litlu gagni vi\u00f0\u00a0 brautarreikninga. \u00deetta breyttist \u00fe\u00f3 me\u00f0 framsetningu Newtons \u00e1ri\u00f0 1687, \u00fear sem hann s\u00fdndi, hvernig finna m\u00e1 massa s\u00f3lar og annarra himinhnatta, til d\u00e6mis jar\u00f0arinnar og J\u00fap\u00edters, \u00fat fr\u00e1 uppl\u00fdsingum um me\u00f0alfjarl\u00e6g\u00f0 og umfer\u00f0art\u00edma fylgihnatta \u00feeirra.<\/p>\n<p>Fyrsti \u00cdslendingurinn, sem vita\u00f0 er me\u00f0 vissu a\u00f0 hafi beitt \u00feri\u00f0ja l\u00f6gm\u00e1linu vi\u00f0 \u00fatreikninga, var l\u00e6risveinn R\u00f6mers, Magn\u00fas Arason. \u00cd disp\u00fatat\u00edunni <a href=\"https:\/\/notendur.hi.is\/einar\/SAGA\/MA_grein_Phases_III.pdf\">Phases lunae<\/a> (F<em>asar tunglsins<\/em>) fr\u00e1 1710 segir Magn\u00fas svo:<\/p>\n<figure id=\"attachment_16266\" aria-describedby=\"caption-attachment-16266\" style=\"width: 424px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-16266\" src=\"https:\/\/uni.hi.is\/einar\/files\/2020\/09\/MA_grein_Phases_III_3jaKeplerslo\u0308gm-300x217.png\" alt=\"\" width=\"424\" height=\"307\" \/><figcaption id=\"caption-attachment-16266\" class=\"wp-caption-text\"><strong>Me\u00f0alfjarl\u00e6g\u00f0ir reikistjarnanna fr\u00e1 s\u00f3linni skv. \u00feri\u00f0ja l\u00f6gm\u00e1li Keplers.<\/strong> Myndin s\u00fdnir reikninga <a href=\"https:\/\/uni.hi.is\/einar\/2019\/11\/26\/magnus-arason-landmaelingamadur\/\">Magn\u00fasar Arasonar<\/a> \u00e1 s\u00ed\u00f0u 6 \u00ed s\u00ed\u00f0ustu disp\u00fatat\u00edu hans um fasa tunglsins fr\u00e1 1710. Hann byrjar \u00e1 ystu reikistj\u00f6rnunni, Sat\u00farnusi. Umfer\u00f0art\u00edmi hennar er 29 <a href=\"https:\/\/en.wikipedia.org\/wiki\/Julian_year_(astronomy)\">j\u00fal\u00ed\u00f6nsk \u00e1r<\/a> og 155 dagar, samtals 10747 dagar. \u00deri\u00f0ja r\u00f3tin af \u00feeirri t\u00f6lu er 22,07 og me\u00f0 \u00fev\u00ed a\u00f0 hefja \u00fatkomuna \u00ed anna\u00f0 veldi f\u00e6st 487. \u00deri\u00f0ja r\u00f3tin af umfer\u00f0art\u00edma jar\u00f0ar, 365 d\u00f6gum, er 7,16, sem \u00ed \u00f6\u00f0ru veldi er 51,07. Fjarl\u00e6g\u00f0 jar\u00f0ar fr\u00e1 s\u00f3linni er 12900 jar\u00f0ar\u00feverm\u00e1l. Samkv\u00e6mt \u00feri\u00f0ja l\u00f6gm\u00e1li Keplers, sem sett er fram \u00e1 s\u00ed\u00f0unni \u00e1 undan me\u00f0 beinni tilvitnun \u00ed 4. bindi af <em>Epitome<\/em> Keplers (bls. 501), f\u00e6st \u00fe\u00e1 fjarl\u00e6g\u00f0 Sar\u00farnusar fr\u00e1 s\u00f3linni me\u00f0 \u00fer\u00edli\u00f0u: (487\/51,07) x 12.900 = 122.920 jar\u00f0ar\u00feverm\u00e1l. \u00c1 sama h\u00e1tt m\u00e1 reikna fjarl\u00e6g\u00f0ir hinna reikistjarnanna, J\u00fap\u00edters, Mars, Venusar og Merk\u00far\u00edusar.<\/figcaption><\/figure>\n<p>\u00dea\u00f0 var hins vegar \u00e1ri\u00f0 1798, sem \u00feri\u00f0ja l\u00f6gm\u00e1l Keplers var fyrst sett fram \u00e1 prenti \u00e1 \u00edslensku. \u00dea\u00f0 var \u00ed ne\u00f0anm\u00e1lsgrein vi\u00f0 <em>N\u00e1tt\u00farusko\u00f0ara<\/em> Suhms \u00e1 bls. 100. \u00dear notast J\u00f3n l\u00e6r\u00f0i J\u00f3nsson vi\u00f0 <a href=\"https:\/\/books.google.is\/books?id=wekqAAAAcAAJ&amp;hl=is&amp;source=gbs_navlinks_s\">kennslub\u00f3k<\/a> C. Horrebows og segir:<\/p>\n<blockquote><p>Stj\u00f6rnu-meistarar fundid hafa, ad Gud gj\u00f6rt hafi \u00e1 vissri fjarl\u00e6gdar tilt\u00f6lu hv\u00f6rrar pl\u00e1netu, sem er s\u00fa: ad \u00fe\u00e6r ferhyrndu edur quadrat-t\u00f6lur \u00feeirra umhlaups-t\u00edma, sem eru \u00ed s\u00f6mu hlutf\u00f6llum s\u00edn \u00e1 millum, sem \u00fe\u00e6r ferstrendu k\u00fab\u00edk-t\u00f6lur \u00feeirrar fjarl\u00e6gdar. \u00deegar madur n\u00fa veit umhlaups-t\u00edma edur \u00e1rslengd tveggja pl\u00e1neta, er h\u00e6gt med \u00feriggja-lida-reglu, ad finna fjarl\u00e6gd annarar \u00feeirra fr\u00e1 s\u00f3lunni, viti madur \u00e1dur hvad \u00f6nnur er l\u00e1ngt \u00ed burtu.<\/p><\/blockquote>\n<p>\u00cd lokin m\u00e1 geta \u00feess, a\u00f0 eftirma\u00f0ur C. Horrebows, Th. Bugge, f\u00f3r vandlega yfir l\u00f6gm\u00e1l Keplers \u00ed fyrirlestrum vi\u00f0 Hafnarh\u00e1sk\u00f3la, sem \u00fdmsir \u00cdslendingar s\u00f3ttu. \u00deetta m\u00e1 til d\u00e6mis sj\u00e1 af <a href=\"https:\/\/books.google.is\/books?id=eoVaAAAAcAAJ&amp;hl=is&amp;source=gbs_navlinks_s\">b\u00f3k hans um stj\u00f6rnufr\u00e6\u00f0i<\/a> fr\u00e1 1796 (bls. 113-119). \u00c1 fyrsta fj\u00f3r\u00f0ungi n\u00edtj\u00e1ndu aldar voru l\u00f6gm\u00e1lin, a\u00f0 minnsta kosti \u00fea\u00f0 fyrsta, \u00feegar or\u00f0in hluti af almennri \u00feekkingu uppl\u00fdstra leikmanna \u00ed Danm\u00f6rku, \u00fe\u00f3tt \u00feau v\u00e6ru ekki alltaf tengd vi\u00f0 nafn Keplers. \u00c1 \u00cdslandi ur\u00f0u \u00feau <a href=\"https:\/\/uni.hi.is\/einar\/2019\/09\/09\/h-c-orsted-bein-og-obein-ahrif-hans-a-islendinga-og-upphaf-kennslu-i-edlisfraedi-og-stjornufraedi-vid-reykjavikurskola\/\">hluti af n\u00e1msefni \u00ed e\u00f0lis- og stj\u00f6rnufr\u00e6\u00f0i<\/a> fr\u00e1 og me\u00f0 stofnun Reykjav\u00edkursk\u00f3la hausti\u00f0 1846.<\/p>\n<ul>\n<li>J. L. Russell, 1964: <a href=\"https:\/\/www.jstor.org\/stable\/4025081?seq=1#metadata_info_tab_contents\">Kepler&#8217;s Laws of Planetary Motion: 1609-1666<\/a>.<\/li>\n<li>B. S. Baigrie, 1987: <a href=\"https:\/\/www.academia.edu\/40474866\/Keplers_laws_of_planetary_motion_before_and_after_Newtons_Principia_An_essay_on_the_transformation_of_scientific_problems\">Kepler&#8217;s Laws of Planetary Motion, before and after Newton&#8217;s Principia<\/a>.<\/li>\n<li>W. Applebaum, 1996: <a href=\"http:\/\/articles.adsabs.harvard.edu\/pdf\/1996HisSc..34..451A\">Keplerian Astronomy after Kepler: Researches and Problems<\/a>.<\/li>\n<li>B. R. Goldstein &amp; G. Hon, 2005: <a href=\"https:\/\/www.academia.edu\/9609775\/Keplers_Move_from_Orbs_to_Orbits_Documenting_a_Revolutionary_Scientific_Concept\">Kepler&#8217;s Move from Orbs to Orbits: Documenting a Revolutionary Scientific Concept<\/a>.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3 style=\"text-align: center\"><span style=\"font-size: 14pt\"><strong>Hreyfiafli\u00f0 \u00ed s\u00f3lkerfinu<\/strong><\/span><em><strong><br \/>\n<\/strong><\/em><\/h3>\n<p>\u00cd jar\u00f0mi\u00f0jukenningum fornaldar og mi\u00f0alda hreyf\u00f0ust f\u00f6ruhnettir og fastastj\u00f6rnur me\u00f0 <a href=\"https:\/\/en.wikipedia.org\/wiki\/Celestial_spheres\">hvelum s\u00ednum<\/a> umhverfis j\u00f6r\u00f0ina. Hreyfiafli\u00f0 kom \u00fdmist a\u00f0 ofan, fr\u00e1 svok\u00f6llu\u00f0u <a href=\"https:\/\/en.wikipedia.org\/wiki\/Primum_Mobile\">frumhreyfihveli<\/a>, sem umkringdi stj\u00f6rnuheiminn, e\u00f0a stafa\u00f0i fr\u00e1 yfirskilvitlegum fyrirb\u00e6rum af \u00fdmsu tagi, svo sem \u00f6ndum e\u00f0a s\u00e1lum f\u00f6ruhnattanna e\u00f0a \u00fe\u00e1 englum, sem st\u00fdr\u00f0u hvelunum. \u00der\u00e1tt fyrir fj\u00f6lda mismunandi <a href=\"https:\/\/en.wikipedia.org\/wiki\/Dynamics_of_the_celestial_spheres\">tilrauna til sk\u00fdringar<\/a> \u00ed gegnum aldirnar, n\u00e1\u00f0ist aldrei samkomulag um \u00fea\u00f0, hvernig \u00fatf\u00e6ra skyldi hugmyndirnar \u00ed sm\u00e1atri\u00f0um.<\/p>\n<p>Keplers byrja\u00f0i snemma a\u00f0 velta \u00fev\u00ed fyrir s\u00e9r, hva\u00f0 g\u00e6ti orsaka\u00f0 hreyfingar reikistjarnanna eftir sporbaugum. Hann komst flj\u00f3tlega a\u00f0 \u00feeirri ni\u00f0urst\u00f6\u00f0u, a\u00f0 hreyfiafli\u00f0 hlyti a\u00f0 b\u00faa \u00ed s\u00f3linni, sj\u00e1lfri mi\u00f0junni, sem veitti \u00f6llu kerfinu lj\u00f3s og yl.\u00a0 Me\u00f0 t\u00edmanum \u00fer\u00f3a\u00f0i hann \u201ee\u00f0lisfr\u00e6\u00f0ilega kenningu\u201c, sem me\u00f0al annars var reifu\u00f0 \u00ed <em>Astronomia nova<\/em> \u00e1ri\u00f0 1609 og a\u00f0 lokum \u00ed endanlegri mynd \u00ed <em>Epitome<\/em> \u00ferett\u00e1n \u00e1rum s\u00ed\u00f0ar.<\/p>\n<p>\u00c1ri\u00f0 1600 kom \u00fat riti\u00f0 <a href=\"https:\/\/archive.org\/details\/GuilielmiGilber00Gilb\/page\/n5\/mode\/2up\">De magnete<\/a> (<em>Um segulinn<\/em>; <a href=\"https:\/\/archive.org\/details\/williamgilbertof00gilbrich\/page\/n7\/mode\/2up\">ensk \u00fe\u00fd\u00f0ing<\/a>; <a href=\"https:\/\/en.wikipedia.org\/wiki\/De_Magnete\">umfj\u00f6llun<\/a>) eftir <a href=\"https:\/\/en.wikipedia.org\/wiki\/William_Gilbert_(physician)\">W. Gilbert<\/a>, \u00fear sem me\u00f0al annars var s\u00fdnt fram \u00e1, a\u00f0 j\u00f6r\u00f0in v\u00e6ri segull. \u00deessi ni\u00f0ursta\u00f0a, sem og b\u00f3kin \u00f6ll, haf\u00f0i mikil \u00e1hrif \u00e1 Kepler, sem setti strax fram \u00fe\u00e1 hugmynd, a\u00f0 hinar reikistj\u00f6rnurnar og s\u00f3lin v\u00e6ru l\u00edka seglar. \u00deetta nota\u00f0i hann \u00ed hugmyndum s\u00ednum um hreyfiafli\u00f0 \u00ed s\u00f3lkerfinu.<\/p>\n<p>Samkv\u00e6mt kenningunni geislar hreyfiafli\u00f0 fr\u00e1 s\u00f3linni l\u00edkt og lj\u00f3s og dofnar me\u00f0 fjarl\u00e6g\u00f0 eins og lj\u00f3s og segulafl. S\u00f3lin sn\u00fdst og aflgeislarnir me\u00f0 henni og \u00feeir draga reikistj\u00f6rnurnar me\u00f0 s\u00e9r \u00ed einskonar hvirfli. Segulafl s\u00f3lar verkar jafnframt beint \u00e1 reikistj\u00f6rnuseglana og f\u00e6rir \u00fe\u00e1 \u00fdmist n\u00e6r e\u00f0a fj\u00e6r s\u00f3linni. Aflei\u00f0ingin ver\u00f0ur s\u00fa, a\u00f0 brautir hnattanna v\u00edkja fr\u00e1 hringl\u00f6gun og ver\u00f0a a\u00f0 sporbaugum.<\/p>\n<figure id=\"attachment_13975\" aria-describedby=\"caption-attachment-13975\" style=\"width: 324px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-13975\" src=\"http:\/\/uni.hi.is\/einar\/files\/2019\/12\/Kepler_Epitomes_-IV-293x300.jpg\" alt=\"\" width=\"324\" height=\"332\" srcset=\"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2019\/12\/Kepler_Epitomes_-IV-293x300.jpg 293w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2019\/12\/Kepler_Epitomes_-IV-768x785.jpg 768w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2019\/12\/Kepler_Epitomes_-IV.jpg 802w\" sizes=\"auto, (max-width: 324px) 100vw, 324px\" \/><figcaption id=\"caption-attachment-13975\" class=\"wp-caption-text\"><span style=\"font-size: 10pt\">Ein af myndum Keplers \u00ed 4. bindi <em>Epitome<\/em> fr\u00e1 1622 (bls. 520 og 588). H\u00fan \u00e1 a\u00f0 hj\u00e1lpa lesandanum til a\u00f0 skilja, hvernig s\u00f3lin dregur reikistj\u00f6rnurnar me\u00f0 s\u00e9r eftir sporbaugsbrautum samkv\u00e6mt hugmyndum h\u00f6fundarins.<\/span><\/figcaption><\/figure>\n<p>\u00deessi kenning Keplers vir\u00f0ist hafa haft l\u00edtil \u00e1hrif \u00e1 n\u00e1tt\u00faruspekinga og stj\u00f6rnufr\u00e6\u00f0inga samt\u00edmans, sennilega vegna \u00feess, a\u00f0 menn voru lengi a\u00f0 venjast \u00feeirri hugsun a\u00f0 nota m\u00e6tti aflfr\u00e6\u00f0i til a\u00f0 \u00fatsk\u00fdra hreyfingar reikistjarnanna. Fyrsti spekingurinn, sem \u00e9g veit til a\u00f0 hafi fjalla\u00f0 opinberlega um kenningu Keplers, var <a href=\"https:\/\/en.wikipedia.org\/wiki\/Gottfried_Wilhelm_Leibniz\">Leibniz<\/a> \u00ed ritger\u00f0 um aflfr\u00e6\u00f0i himintungla, <a href=\"http:\/\/www.17centurymaths.com\/contents\/Leibniz\/ae10.pdf\">Tentamen de motuum coelestium causis<\/a>, \u00e1ri\u00f0 1689. R\u00e9tt er \u00fe\u00f3 a\u00f0 geta \u00feess, a\u00f0 \u00f3h\u00e1\u00f0 Kepler setti Gal\u00edle\u00f3 fram \u00fe\u00e1 hugmynd, a\u00f0 reikistj\u00f6rnurnar snerust um s\u00f3lina vegna m\u00f6ndulsn\u00fanings hennar, en hann \u00fatf\u00e6r\u00f0i \u00fe\u00e1 hugmynd aldrei n\u00e1nar.<\/p>\n<p>Mikilv\u00e6gt er a\u00f0 hafa \u00ed huga, a\u00f0 \u00ed hreyfiaflskenningu Keplers er hvergi minnst \u00e1 a\u00f0dr\u00e1ttarafl og \u00feyngdin kemur \u00fear hvergi vi\u00f0 s\u00f6gu. Kepler haf\u00f0i a\u00f0 sj\u00e1lfs\u00f6g\u00f0u s\u00ednar eigin hugmyndir um \u00feyngdina og vir\u00f0ist hafa tali\u00f0, a\u00f0 h\u00fan v\u00e6ri n\u00e6r eing\u00f6ngu bundin vi\u00f0 j\u00f6r\u00f0ina og v\u00e6ri einna l\u00edkust segulafli.<\/p>\n<p>Hugmynd hans var s\u00fa, a\u00f0 \u201ee\u00f0lisl\u00edkir hlutir\u201c dr\u00e6gjust hver a\u00f0 \u00f6\u00f0rum. \u00dea\u00f0 v\u00e6ri \u00e1st\u00e6\u00f0an fyrir \u00fev\u00ed, a\u00f0 efnishlutar jar\u00f0arinnar h\u00e9ldust saman, jafnvel \u00fe\u00f3tt h\u00fan v\u00e6ri ekki \u00ed mi\u00f0ju heimsins, eins og gert var r\u00e1\u00f0 fyrir \u00ed jar\u00f0mi\u00f0jukenningum. A\u00f0 auki vir\u00f0ist Kepler hafa tali\u00f0, a\u00f0 \u00feetta a\u00f0dr\u00e1ttarafl v\u00e6ri skammdr\u00e6gt og hann velti \u00fev\u00ed \u00feess vegna ekkert fyrir s\u00e9r, hvort \u00fea\u00f0 breyttist me\u00f0 fjarl\u00e6g\u00f0 milli hlutanna (sj\u00e1 n\u00e1nar <a href=\"https:\/\/en.wikipedia.org\/wiki\/Astronomia_nova#Kepler's_knowledge_of_gravity\">h\u00e9r<\/a>).<\/p>\n<p>\u00cd <em>N\u00e1tt\u00farusko\u00f0ara<\/em> m\u00e1 finna umfj\u00f6llun, sem tengst hugmyndum Keplers (og einnig Descartes) um \u00feyngdina. \u00dear segir Suhm \u00e1 bls. 14-16:<\/p>\n<blockquote><p>J\u00f6rdin hn\u00fdgur med \u00fe\u00fdngd sinni a\u00f0 midp\u00fankti, hennar partar halda s\u00e9r \u00feess vegna \u00fe\u00e9tt saman <em>[\u2026]<\/em> En hvad er \u00fe\u00fdngdin \u00ed sj\u00e1lfri s\u00e9r, og \u00ed hv\u00f6rju er h\u00fan f\u00f3lgin? H\u00e9r hlj\u00f3tum v\u00e9r oss h\u00f6nd \u00e1 munn ad leggja, og vidurk\u00e9nna ad Guds v\u00edsd\u00f3mur tekur l\u00e1ngt fram vorri \u00feeckingu; samt sem \u00e1dur er \u00fe\u00fdngdin og hennar l\u00f6g \u00ed n\u00e1tt\u00farunni oss nockurnveginn kunnug, og l\u00edka \u00fear af flj\u00f3tandi misj\u00f6fnudur \u00ed hr\u00e6ringunum, er r\u00edsa af \u00fev\u00ed ad einn hlutur \u00feryckir \u00f8drum, edur steytir \u00e1 annann.<\/p><\/blockquote>\n<p>Og ne\u00f0anm\u00e1ls v\u00edsar J\u00f3n J\u00f3nsson \u00ed d\u00f6nsku \u00fe\u00fd\u00f0inguna af b\u00f3k <a href=\"https:\/\/en.wikipedia.org\/wiki\/William_Derham\">W. Derham<\/a>s, <em>Astro- et physico-Theologie<\/em> fr\u00e1 1759, og b\u00e6tir vi\u00f0:<\/p>\n<blockquote><p>V\u00e6ri ecki \u00feessi eginnlegleikur j\u00f6rdunni af Skaparanum gefinn, fyrir hv\u00f6rn ad allir hennar samanstandandi partar dragast svo fast saman, kynni h\u00fan ei ad standast, \u00fev\u00ed ella hryndi h\u00fan \u00e1 augabragdi \u00f6ll sundur \u00ed sm\u00e1 mola, vegna hennar yfrid hvatskeytlega sn\u00fanings og flugs \u00e1fram kr\u00edngum s\u00f3lina <em>[\u2026]<\/em> En M\u00e6lingameistarar reikna a\u00f0 kraptur s\u00e1, sem heldur j\u00f6rdunni saman fyrir \u00fe\u00fdngdina, s\u00e9 288sinnum meiri \u00feeim, sem sundurdreifa vill hennar samstandandi p\u00f6rtum.<\/p><\/blockquote>\n<p>Talan 288, sem \u00fearna er nefnd, er komin fr\u00e1 Descartes.<\/p>\n<ul>\n<li>E. McMullin, 2011: <a href=\"https:\/\/www.jstor.org\/stable\/10.1086\/658917?seq=1#metadata_info_tab_contents\">Kepler: Moving the Earth<\/a>.<\/li>\n<li>W. Applebaum &amp; R. Baldasso, 2001: <a href=\"http:\/\/fundacionorotava.org\/media\/web\/files\/page145__cap_03_04_Applebaum_Baldasso.pdf\">Galileo and Kepler on the Sun as Planetary Mover<\/a>.<\/li>\n<li>R. S. Westman, 2001: <a href=\"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/002182860103200304\">Kepler&#8217;s Early Physical-Astrological Problematic<\/a>.<\/li>\n<li>E. Hecht, 2019: <a href=\"https:\/\/aapt.scitation.org\/doi\/abs\/10.1119\/1.5089751?\">Kepler and the origins of the theory of gravity<\/a>.<\/li>\n<\/ul>\n<p>Vangaveltur um st\u00e6r\u00f0 alheimsins ver\u00f0a til umr\u00e6\u00f0u \u00ed seinni f\u00e6rslum og \u00fev\u00ed er vi\u00f0 h\u00e6fi a\u00f0 nefna \u00fea\u00f0 h\u00e9r, a\u00f0 alheimur Keplers var afmarka\u00f0ur og endanlegur. Fyrir \u00fev\u00ed f\u00e6r\u00f0i hann sterk e\u00f0lisfr\u00e6\u00f0ileg r\u00f6k, sem hann birti \u00ed opnu br\u00e9fi til Gal\u00edle\u00f3s \u00e1ri\u00f0 1610, <a href=\"https:\/\/books.google.is\/books?id=jBSq5Bx_NekC&amp;source=gbs_navlinks_s\">Dissertatio cum nuncio sidereo<\/a> (<em>Samtal vi\u00f0 sendibo\u00f0a stjarnanna<\/em>; <a href=\"http:\/\/digitalcollections.library.cmu.edu\/awweb\/awarchive?type=file&amp;item=393654\">ensk \u00fe\u00fd\u00f0ing<\/a>). \u00dear beitir Kepler \u00feekkingu sinni \u00ed lj\u00f3sfr\u00e6\u00f0i og s\u00fdnir fram \u00e1, a\u00f0 \u00ed \u00f3endanlegum og st\u00f6\u00f0ugum stj\u00f6rnuheimi er \u00f6ll hvelfingin \u00e1vallt jafn bj\u00f6rt og stj\u00f6rnuyfirbor\u00f0. \u00cd sl\u00edkum heimi er \u00fev\u00ed jafn bjart \u00e1 n\u00f3ttu sem degi. Eins og allir vita er myrkur \u00e1 n\u00f3ttinni og af \u00fev\u00ed lei\u00f0ir, a\u00f0 stj\u00f6rnuheimurinn hl\u00fdtur a\u00f0 vera endanlegur. \u00deessi r\u00f6ksemdaf\u00e6rsla er n\u00fana \u00feekkt undir nafninu <a href=\"https:\/\/en.wikipedia.org\/wiki\/Olbers%27_paradox\">\u00fevers\u00f6gn Olbers<\/a>. \u00der\u00e1tt fyrir \u201es\u00f6nnun\u201c Keplers, t\u00f3k Gal\u00edle\u00f3 aldrei endanlega afst\u00f6\u00f0u til \u00feess, hvort stj\u00f6rnuheimurinn v\u00e6ri \u00f3endanlegur e\u00f0a ekki.<\/p>\n<ul>\n<li>M. A. Granada, 2008: <a href=\"http:\/\/articles.adsabs.harvard.edu\/\/full\/2008JHA....39..469T\/0000470.000.html\">Kepler and Bruno on the Infinity of the Universe and of Solar Systems<\/a>.<\/li>\n<li>E. Harrison, 1987: <a href=\"https:\/\/books.google.is\/books?id=IRKYueWVftYC&amp;source=gbs_navlinks_s\">Darkness at Night: A Riddle of the Universe<\/a>.<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3 style=\"text-align: center\"><span style=\"font-size: 14pt\"><strong>\u00d6rl\u00edtil vi\u00f0b\u00f3t um \u00fer\u00f3unina fr\u00e1 K\u00f3pern\u00edkusi til Newtons<\/strong><\/span><\/h3>\n<p>\u00dea\u00f0 t\u00f3k <a href=\"https:\/\/en.wikipedia.org\/wiki\/Copernican_heliocentrism\">s\u00f3lmi\u00f0jukenninguna<\/a> mun lengri t\u00edma en margir halda a\u00f0 vinna sigur \u00e1 hinum fornu jar\u00f0mi\u00f0juhugmyndum,\u00a0 s\u00e9rstaklega \u00fe\u00f3 \u00feeirri, sem bygg\u00f0 er \u00e1 <a href=\"https:\/\/en.wikipedia.org\/wiki\/Almagest\">Almagest<\/a>, hinu mikla verki\u00a0 <a href=\"https:\/\/en.wikipedia.org\/wiki\/Ptolemy\">Pt\u00f3lema\u00edosar<\/a> fr\u00e1 annarri \u00f6ld. Reyndar h\u00f6f\u00f0u margir stj\u00f6rnufr\u00e6\u00f0ingar \u00feegar gefist upp \u00e1 hugmyndum hans \u00ed lok sext\u00e1ndu aldar, en \u00ed sta\u00f0in var \u00fe\u00e1 komin <a href=\"https:\/\/en.wikipedia.org\/wiki\/Tychonic_system\">n\u00fd jar\u00f0mi\u00f0jukenning<\/a>, kennd vi\u00f0 T\u00fdch\u00f3 Brahe. S\u00fa kenning naut mikillar hylli allt fram yfir mi\u00f0ja sautj\u00e1ndu \u00f6ld, ekki s\u00edst me\u00f0al <a href=\"https:\/\/en.wikipedia.org\/wiki\/Society_of_Jesus\">Jes\u00fa\u00edta<\/a> og annarra ka\u00fe\u00f3likka, sem og Dana.<\/p>\n<p>\u00cd kerfi Brahes er j\u00f6r\u00f0in \u00ed mi\u00f0ju heimsins. Um\u00a0 hana ganga tungli\u00f0 og s\u00f3lin, en allir a\u00f0rir f\u00f6ruhnettir sn\u00faast um s\u00f3lina (sj\u00e1 mynd h\u00e9r fyrir ne\u00f0an). \u00deessi n\u00fdi keppinautur s\u00f3lmi\u00f0jukenningarinnar kom fyrst \u00e1 prenti \u00e1ri\u00f0 1588 \u00ed riti Brahes, <a href=\"https:\/\/archive.org\/stream\/bub_gb_2f-EqKxRN34C#page\/n0\/mode\/2up\">De mundi aetherei recentioribus phaenomenis<\/a> (<em>Um n\u00fdleg fyrirb\u00e6ri \u00ed vakaheimi<\/em>; <a href=\"https:\/\/en.wikipedia.org\/wiki\/Tychonic_system\">umfj\u00f6llun<\/a>). \u00dea\u00f0 var \u00fe\u00f3 ekki fyrr en Gal\u00edle\u00f3 haf\u00f0i sk\u00fdrt fr\u00e1 hinum m\u00f6gnu\u00f0u sj\u00f3naukaathugunum s\u00ednum \u00ed <a href=\"http:\/\/lhldigital.lindahall.org\/cdm\/ref\/collection\/astro_early\/id\/68\">Sidereus nuncius<\/a> (<em>Sendibo\u00f0i stjarnanna<\/em>;<a href=\"https:\/\/books.google.is\/books?id=k6xrCwAAQBAJ&amp;source=gbs_navlinks_s\"> ensk \u00fe\u00fd\u00f0ing<\/a>; <a href=\"https:\/\/en.wikipedia.org\/wiki\/Sidereus_Nuncius\">umfj\u00f6llun<\/a>) \u00e1ri\u00f0 1610, sem m\u00e1lsvarar jar\u00f0mi\u00f0jukenningarinnar, einkum Jes\u00fa\u00edtar, gripu fyrir alv\u00f6ru til varna me\u00f0 heimsmynd Brahes a\u00f0 vopni. H\u00fan gat nefnilega \u00fatsk\u00fdrt flestar af athugunum Gal\u00edle\u00f3s jafn au\u00f0veldlega og s\u00f3lmi\u00f0jukenningin.<\/p>\n<p>\u00deekktasta rit Jes\u00fa\u00edta um \u00feetta og tengd efni er <a href=\"https:\/\/books.google.is\/books?id=_mJDAAAAcAAJ&amp;source=gbs_navlinks_s\">Almagestum novum<\/a> (<em>Hi\u00f0 n\u00fdja Almagest; <a href=\"https:\/\/books.google.is\/books?id=IWNDAAAAcAAJ&amp;source=gbs_navlinks_s\">framhald h\u00e9r<\/a>; <\/em><a href=\"https:\/\/en.wikipedia.org\/wiki\/Giovanni_Battista_Riccioli#Almagestum_Novum\">umfj\u00f6llun<\/a>) fr\u00e1 1651. H\u00f6fundurinn <a href=\"https:\/\/en.wikipedia.org\/wiki\/Giovanni_Battista_Riccioli\">G. B. Riccioli<\/a> var \u00ed h\u00f3pi merkustu n\u00e1tt\u00faruspekinga \u00e1 fyrri hluta sautj\u00e1ndu aldar, en til skamms t\u00edma hefur l\u00edti\u00f0 veri\u00f0 um hann fjalla\u00f0 \u00ed s\u00f6gub\u00f3kum, sennilega vegna \u00feess a\u00f0 hann starfa\u00f0i \u00ed skugga \u00feekktari einstaklinga, eins og Keplers, Gal\u00edle\u00f3s og Descartes.<\/p>\n<ul>\n<li>L. M. Carolino, 2008: <a href=\"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1177\/002182860803900303\">The Making of a Tychonic Cosmology: Cristoforo Borri and the Development of Tycho Brahe&#8217;s Astronomical System<\/a>.<\/li>\n<li>C. M. Graney, 2015: <a href=\"https:\/\/undpress.nd.edu\/9780268029883\/setting-aside-all-authority\/\">Setting Aside All Authority: Giovanni Battista Riccioli and the Science against Copernicus in the Age of Galileo<\/a>.<\/li>\n<\/ul>\n<p>\u00c1ri\u00f0 1632 kom \u00fat hi\u00f0 mikla rit Gal\u00edle\u00f3s, <a href=\"https:\/\/archive.org\/details\/dialogodigalileo00gali\/page\/n7\/mode\/2up\">Dialogo [&#8230;] sopra i due massimi sistemi del mondo Tolemaico, e Copernican<\/a> (<em>Samr\u00e6\u00f0ur um heimskerfi Pt\u00f3lema\u00edosar og K\u00f3pern\u00edkusar;<\/em> <a href=\"http:\/\/actascientiae.org\/Galileo_Galilei_Dialogue_Concerning_the_Two_Chief_World_Systems.pdf\">ensk \u00fe\u00fd\u00f0ing<\/a>; <a href=\"https:\/\/en.wikipedia.org\/wiki\/Dialogue_Concerning_the_Two_Chief_World_Systems\">umfj\u00f6llun<\/a>), verki\u00f0 sem var\u00f0 kveikjan a\u00f0 deilum hans vi\u00f0 ka\u00fe\u00f3lska kirkjuvaldi\u00f0. Svo vir\u00f0ist, sem ein af \u00e1st\u00e6\u00f0unum fyrir vi\u00f0br\u00f6g\u00f0um kirkjunnar hafi veri\u00f0, a\u00f0 \u00ed b\u00f3kinni beinir Gal\u00edle\u00f3 spj\u00f3tum s\u00ednum b\u00e6\u00f0i a\u00f0 kenningum Pt\u00f3lema\u00edosar og Brahes, \u00e1n \u00feess \u00fe\u00f3 a\u00f0 nefna Brahe nokkurs sta\u00f0ar \u00e1 nafn. Gal\u00edle\u00f3 mun nefnilega hafa lofa\u00f0 kirkjunnar m\u00f6nnum a\u00f0 l\u00e1ta kenningu Brahes \u00ed fri\u00f0i og fjalla a\u00f0eins um heimsmynd Pt\u00f3lema\u00edosar, sem kirkjan leit \u00fe\u00e1 \u00feegar \u00e1 sem \u00farelta kenningu. \u00deetta mun, \u00e1samt \u00f6\u00f0ru, hafa reitt kirkjuh\u00f6f\u00f0ingjana til rei\u00f0i, me\u00f0 aflei\u00f0ingum sem allir \u00feekkja.<\/p>\n<ul>\n<li>H. Margolis, 1991: <a href=\"https:\/\/www.sciencedirect.com\/science\/article\/abs\/pii\/003936819190027P\">Tycho\u2019s system and Galileo\u2019s Dialogue<\/a>.<\/li>\n<\/ul>\n<p>\u00cd disp\u00fatat\u00edu G\u00edsla \u00deorl\u00e1kssonar fr\u00e1 1651, <a href=\"https:\/\/notendur.hi.is\/einar\/SAGA\/DStellis.pdf\">De stellis fixis et errantibus<\/a> (<em>Um fastastj\u00f6rnur og f\u00f6ruhnetti;<\/em> <a href=\"https:\/\/uni.hi.is\/einar\/2017\/10\/02\/fyrsta-prentada-ritgerdin-um-stjornufraedi-eftir-islenskan-hofund\/\">umfj\u00f6llun<\/a>), er me\u00f0al annars fjalla\u00f0 um deilurnar milli fylgismanna K\u00f3pern\u00edkusar og Brahes. \u00dear er og minnist \u00e1 \u00fdmsar ni\u00f0urst\u00f6\u00f0ur Gal\u00edle\u00f3s, \u00e1n \u00feess \u00fe\u00f3 a\u00f0 hann s\u00e9 nefndur \u00e1 nafn! Til d\u00e6mis r\u00e6\u00f0ir G\u00edsli um hluta af r\u00f6kunum \u00ed <em>Dialogo<\/em> gegn jar\u00f0mi\u00f0jukenningunni, eins og sj\u00e1 m\u00e1 \u00ed eftirfarandi myndatexta:<\/p>\n<figure id=\"attachment_14850\" aria-describedby=\"caption-attachment-14850\" style=\"width: 629px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-14850\" src=\"https:\/\/uni.hi.is\/einar\/files\/2020\/05\/BraheGalileo_2-300x193.png\" alt=\"\" width=\"629\" height=\"405\" srcset=\"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/BraheGalileo_2-300x193.png 300w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/BraheGalileo_2-1024x658.png 1024w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/BraheGalileo_2-768x494.png 768w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/BraheGalileo_2-1536x987.png 1536w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/BraheGalileo_2.png 1553w\" sizes=\"auto, (max-width: 629px) 100vw, 629px\" \/><figcaption id=\"caption-attachment-14850\" class=\"wp-caption-text\"><span style=\"font-size: 10pt\">Til vinstri: Jar\u00f0mi\u00f0juheimur Brahes \u00far b\u00f3k hans <em>Um n\u00fdleg fyrirb\u00e6ri<\/em> fr\u00e1 1588 (bls.189).\u00a0 Til h\u00e6gri: S\u00f3lmi\u00f0juheimur Gal\u00edle\u00f3s \u00far b\u00f3k hans <em>Samr\u00e6\u00f0ur um heimskerfin <\/em>fr\u00e1 1632 (bls. 520).\u00a0 &#8211;\u00a0 \u00cd sta\u00f0h\u00e6fingum XV og XVI \u00ed disp\u00fatat\u00edunni <em>Um fastastj\u00f6rnur og f\u00f6ruhnetti<\/em> fr\u00e1 1651 segir G\u00edsli \u00deorl\u00e1ksson me\u00f0al annars um \u00feessi heimskerfi:\u00a0 \u201eTalsmenn kerfis K\u00f3pern\u00edkusar finna kerfum Pt\u00f3lema\u00edosar og T\u00fdch\u00f3s margt til for\u00e1ttu, einkum \u00fe\u00f3 a\u00f0 hvorugur \u00feeirra hafi stutt \u00fea\u00f0 traustum r\u00f6kum a\u00f0 j\u00f6r\u00f0in s\u00e9 \u00ed mi\u00f0ju alheimsins. En \u00f3bilgirni \u00feeirra dylst \u00fe\u00f3 engum, \u00fev\u00ed sj\u00e1lfir hafa \u00feeir ekki enn s\u00fdnt \u00f3yggjandi fram \u00e1, a\u00f0 velja eigi s\u00f3linni sta\u00f0 \u00ed mi\u00f0ju heimsins. Hvers vegna heimta \u00feeir svo af \u00f6\u00f0rum \u00fea\u00f0 sem \u00feeir geta ekki sj\u00e1lfir afreka\u00f0?\u00a0 \u00deegar \u00feeir svo telja, a\u00f0 \u00fea\u00f0 fari \u00ed b\u00e1ga vi\u00f0 n\u00e1tt\u00faruna a\u00f0 \u00feau himintungl sem mynda einn alheim hafi tvennar undirst\u00f6\u00f0ur, \u00fea\u00f0 er a\u00f0 segja samkv\u00e6mt fylgism\u00f6nnum Tychos kyrrst\u00e6\u00f0a j\u00f6r\u00f0 og hreyfanlega s\u00f3l, \u00fe\u00e1 vega \u00feeir sig me\u00f0 eigin sver\u00f0i. \u00dev\u00ed sj\u00e1lfir segja \u00feeir a\u00f0 Merk\u00far\u00edus, Venus, j\u00f6r\u00f0in, Mars, J\u00fap\u00edter og Sat\u00farnus hreyfist um s\u00f3lina sem fastan og \u00f3hagganlegan mi\u00f0punkt, en tungli\u00f0 aftur um hreyfanlega j\u00f6r\u00f0ina. Eru \u00fea\u00f0 ekki tvennar undirst\u00f6\u00f0ur: s\u00f3lin og j\u00f6r\u00f0in? Og hva\u00f0 ef s\u00e9st hafi a\u00f0 auki a\u00f0 J\u00fap\u00edters-reikistj\u00f6rnurnar sn\u00faist um hinn hreyfanlega J\u00fap\u00edter?\u201c<\/span><\/figcaption><\/figure>\n<p>\u00dea\u00f0 er ekki n\u00f3g me\u00f0, a\u00f0 G\u00edsli sleppi \u00fev\u00ed a\u00f0 nefna Gal\u00edle\u00f3 \u00ed disp\u00fatat\u00edunni, heldur minnist hann hvorki \u00e1 Kepler n\u00e9 l\u00f6gm\u00e1l hans. \u00dea\u00f0 er sennilega vegna \u00e1hrifa fr\u00e1 nemanda og samstarfsmanni Brahes, <a href=\"https:\/\/en.wikipedia.org\/wiki\/Christen_S%C3%B8rensen_Longomontanus\">Longomontanusi<\/a>, fyrsta pr\u00f3fessornum \u00ed stj\u00f6rnufr\u00e6\u00f0i vi\u00f0 Hafnarh\u00e1sk\u00f3la. B\u00f3k hans <a href=\"https:\/\/books.google.is\/books?id=f1I_AAAAcAAJ&amp;source=gbs_navlinks_s\">Astronomia Danica<\/a> (<em>D\u00f6nsk stj\u00f6rnulist<\/em>; <a href=\"http:\/\/adsabs.harvard.edu\/full\/1987JHA....18...95H\">umfj\u00f6llun<\/a>), sem kom fyrst \u00fat 1622 (aftur 1640 og 1663) haf\u00f0i talsver\u00f0 \u00e1hif og var v\u00ed\u00f0a notu\u00f0 vi\u00f0 kennslu, einkum \u00fe\u00f3 \u00ed sk\u00f3lum Jes\u00fa\u00edta. Longomontanus h\u00e9lt st\u00edft fram heimsmynd kennara s\u00edns og var eindreginn andst\u00e6\u00f0ingur Keplers, fyrrum samstarfsmanns s\u00edns hj\u00e1 Brahe \u00ed Prag. \u00d3s\u00e6tti\u00f0 vi\u00f0 Kepler var \u00e1st\u00e6\u00f0a \u00feess, a\u00f0 fyrrnefndar <em>T\u00f6flur R\u00fad\u00f3lfs<\/em> voru ekki nota\u00f0ar \u00ed Danm\u00f6rku fyrr en \u00e1 s\u00ed\u00f0ustu \u00e1ratugum sautj\u00e1ndu aldar.<\/p>\n<ul>\n<li>K. P. Moesgaard, 1972: <a href=\"https:\/\/books.google.is\/books?id=kCHtCAAAQBAJ&amp;source=gbs_navlinks_s\">How Copernicanism took root in Denmark and Norway<\/a> (bls. 117-152).<\/li>\n<li>H. Kragh, 2o15: <a href=\"https:\/\/www.researchgate.net\/publication\/281161374_Georgius_Frommius_1605-1651_and_Danish_Astronomy_in_the_Post-Tychonian_Era\">Georgius Frommius (1605\u20131651) and Danish Astronomy in the Post-tychonian era<\/a>.<\/li>\n<li>H. Kragh, 2014: <a href=\"https:\/\/arxiv.org\/abs\/1407.7380\">Galileo in early modern Denmark, 1600-1650<\/a>.<\/li>\n<li>Einar H. Gu\u00f0mundsson, Eyj\u00f3lfur Kolbeins og \u00deorsteinn Vilhj\u00e1lmsson, 2006: <a href=\"https:\/\/notendur.hi.is\/~einar\/SAGA\/Kopernik.pdf\">Heimsmyndin \u00ed ritum l\u00e6r\u00f0ra \u00cdslendinga \u00e1 sautj\u00e1ndu og \u00e1tj\u00e1ndu \u00f6ld.<\/a> (Sj\u00e1 heimildaskr\u00e1 bls. 284-89.)<\/li>\n<li>Einar H. Gu\u00f0mundsson, 2010: <a href=\"https:\/\/notendur.hi.is\/~einar\/SAGA\/Heimildir.pdf\">Heimildir \u00cdslendinga um heimsmynd stjarnv\u00edsinda 1550-1750.<\/a><\/li>\n<\/ul>\n<figure id=\"attachment_14725\" aria-describedby=\"caption-attachment-14725\" style=\"width: 479px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-14725\" src=\"https:\/\/uni.hi.is\/einar\/files\/2020\/05\/GalileoDescartes-300x210.jpeg\" alt=\"\" width=\"479\" height=\"335\" srcset=\"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/GalileoDescartes-300x210.jpeg 300w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/GalileoDescartes-768x539.jpeg 768w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/GalileoDescartes.jpeg 924w\" sizes=\"auto, (max-width: 479px) 100vw, 479px\" \/><figcaption id=\"caption-attachment-14725\" class=\"wp-caption-text\"><span style=\"font-size: 10pt\">Til vinstri: <a href=\"https:\/\/en.wikipedia.org\/wiki\/Galileo_Galilei\">Gal\u00edle\u00f3 Gal\u00edle\u00ed<\/a>. M\u00e1lverk eftir Justus Sustermans fr\u00e1 1636\u00a0 &#8211; Til h\u00e6gri: <a href=\"https:\/\/en.wikipedia.org\/wiki\/Ren%C3%A9_Descartes\">Ren\u00e9 Descartes<\/a> \u00e1 m\u00e1lverki eftir Frans Hals eldri (\u00e1rtal \u00f3\u00feekkt).<\/span><\/figcaption><\/figure>\n<p>&nbsp;<\/p>\n<h3 style=\"text-align: center\"><span style=\"font-size: 14pt\"><strong>Hvirflar Descartes<\/strong><\/span><\/h3>\n<p>Samkv\u00e6mt kenningum Descartes eru efni og r\u00fam \u00ed vissum skilningi tv\u00e6r hli\u00f0ar \u00e1 sama fyrirb\u00e6rinu; \u00e1n efnis v\u00e6ri ekkert r\u00fam og \u00f6fugt. Af \u00fev\u00ed lei\u00f0ir a\u00f0 <a href=\"https:\/\/en.wikipedia.org\/wiki\/Vacuum\">t\u00f3m<\/a> er ekki til og geimurinn er fullur af efni, \u00fear sem kvikir efnishlutar n\u00faast saman og mynda \u00f6rlitlar og \u00f3endanlega deilanlegar agnir. Agnirnar, sem eru reyndar \u00ferenns konar hj\u00e1 Descartes, mynda samfellt straumefni (v\u00f6kva) e\u00f0a vaka (eter, plenum). Allir himinhnettir eru samsettir \u00far sam\u00fej\u00f6ppu\u00f0um og gr\u00f3fum afbrig\u00f0um \u00feessa vaka og umhverfist \u00fe\u00e1 eru <a href=\"http:\/\/descartes.cyberbrahma.com\/vortex.html\">hvirflar<\/a> \u00far \u00feynnra straumefni.<\/p>\n<p>Descartes a\u00f0hylltist s\u00f3lmi\u00f0jukenninguna, svo st\u00e6rsti hvirfillinn \u00ed s\u00f3lkerfinu er a\u00f0 sj\u00e1lfs\u00f6g\u00f0u \u00ed kringum s\u00f3lina, og \u00fea\u00f0 er hann sem dregur reikistj\u00f6rnurnar me\u00f0 s\u00e9r umhverfis hana. A\u00f0rar s\u00f3lir hafa einnig s\u00edna hvirfla og alheimur er samsettur \u00far sl\u00edkum fyrirb\u00e6rum, eins og s\u00fdnt er \u00e1 myndinni h\u00e9r fyrir ne\u00f0an. \u00deegar s\u00f3larhvirflar ey\u00f0ist af einhverjum \u00e1st\u00e6\u00f0um, ver\u00f0a \u00feeir a\u00f0 reikistj\u00f6rnum, ef leifar \u00feeirra festast \u00ed n\u00e1l\u00e6gum hvirflum, annars a\u00f0 halastj\u00f6rnum, sem fer\u00f0ast milli hvirfla.<\/p>\n<p>\u00c1ri\u00f0 1633 var Descartes \u00feegar b\u00fainn a\u00f0 semja rit um hvirflakenninguna, <a href=\"https:\/\/books.google.is\/books?id=8MFvasB2qqQC&amp;hl=fr&amp;source=gbs_navlinks_s\">Le Monde<\/a> (<em>Heimurinn<\/em>; <a href=\"https:\/\/www.princeton.edu\/~hos\/mike\/texts\/descartes\/world\/worldfr.htm\">ensk \u00fe\u00fd\u00f0ing<\/a>; <a href=\"https:\/\/en.wikipedia.org\/wiki\/The_World_(book)\">umfj\u00f6llun<\/a>), en vegna r\u00e9ttarhaldanna yfir Gal\u00edle\u00f3 kom \u00fea\u00f0 ekki \u00fat fyrr en a\u00f0 h\u00f6fundi l\u00e1tnum, 1664. \u00cd millit\u00ed\u00f0inni birtist \u00fe\u00f3 hi\u00f0 mikla rit hans <a href=\"https:\/\/books.google.is\/books?id=lHpbAAAAQAAJ&amp;source=gbs_navlinks_s\">Principia philosophiae<\/a> (<em>L\u00f6gm\u00e1l heimspekinnar<\/em>; <a href=\"https:\/\/link.springer.com\/book\/10.1007\/978-94-009-7888-1\">ensk \u00fe\u00fd\u00f0ing<\/a>; <a href=\"https:\/\/en.wikipedia.org\/wiki\/Principles_of_Philosophy\">umfj\u00f6llun<\/a>), \u00fear sem kenningunni eru ger\u00f0 \u00edtarleg skil.<\/p>\n<p>Hvirflakenningin komst flj\u00f3tlega \u00e1 miki\u00f0 flug \u00ed Frakklandi og breiddist \u00fea\u00f0an \u00fat til annarra landa. \u00cd \u00fev\u00ed sambandi m\u00e1 nefna, a\u00f0 minnst var \u00e1 kenninguna \u00e1 prenti \u00ed fyrsta sinn \u00ed Danm\u00f6rku \u00ed \u00e1\u00f0urnefndri disp\u00fatat\u00edu G\u00edsla \u00deorl\u00e1kssonar, <em>Um fastastj\u00f6rnur og f\u00f6ruhnetti<\/em>.\u00a0 Hvirflarnir h\u00e9ldu \u00fe\u00f3 ekki innrei\u00f0 s\u00edna vi\u00f0 Hafnarh\u00e1sk\u00f3la fyrr en me\u00f0 ritum og kennslu <a href=\"https:\/\/mathshistory.st-andrews.ac.uk\/Biographies\/Bartholin\/\">Rasmusar Bartholin<\/a> um og upp \u00far 1660.<\/p>\n<p>\u00c1ri\u00f0 1707 samdi <a href=\"https:\/\/is.wikipedia.org\/wiki\/%C3%9Eorleifur_Halld%C3%B3rsson\">\u00deorleifur Halld\u00f3rsson<\/a> latneska disp\u00fatat\u00edu, <a href=\"https:\/\/uni.hi.is\/einar\/files\/2019\/12\/DeAplane.pdf\">De aplane<\/a>\u00a0 (<em>Um festinguna<\/em>; <a href=\"https:\/\/notendur.hi.is\/~einar\/SAGA\/Kopernik.pdf\">umfj\u00f6llun<\/a> [sj\u00e1 bls. 269]). Ritger\u00f0in fjalla\u00f0i me\u00f0al annars um s\u00f3lmi\u00f0jukenninguna og hvirfla Descartes. Af yfirfer\u00f0inni m\u00e1 sj\u00e1, a\u00f0 \u00deorleifur hefur glugga\u00f0 \u00ed <a href=\"https:\/\/books.google.is\/books?id=l5qu7Aj34d4C&amp;source=gbs_navlinks_s\">Systema cosmicum<\/a>, latnesku \u00fatg\u00e1funa af <em>Dialogo<\/em> Gal\u00edle\u00f3s,\u00a0 en vir\u00f0ist hins vegar ekki hafa lesi\u00f0 rit Descartes. \u00cd umr\u00e6\u00f0unni um hvirflana sty\u00f0st \u00deorleifur \u00ed sta\u00f0inn vi\u00f0 verki\u00f0 <a href=\"https:\/\/books.google.is\/books?id=ZLbC9uTrvkcC&amp;source=gbs_navlinks_s\">Institutio Philosophiae, Secundum Principia D. Renati Descartes<\/a> (<a href=\"http:\/\/lhldigital.lindahall.org\/digital\/collection\/emblematic\/id\/1576\">ensk \u00fe\u00fd\u00f0ing<\/a>) eftir\u00a0<a href=\"https:\/\/en.wikipedia.org\/wiki\/Antoine_Le_Grand\">Antoine Le Grand<\/a>, sem mun hafa veri\u00f0 gr\u00ed\u00f0arlega vins\u00e6l kennslub\u00f3k v\u00ed\u00f0a \u00ed Evr\u00f3pu \u00e1 \u00feessum t\u00edma:<\/p>\n<p><figure id=\"attachment_14910\" aria-describedby=\"caption-attachment-14910\" style=\"width: 385px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\" wp-image-14910\" src=\"https:\/\/uni.hi.is\/einar\/files\/2020\/05\/Descartes_Princ_philo_92-195x300.jpg\" alt=\"\" width=\"385\" height=\"592\" srcset=\"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/Descartes_Princ_philo_92-195x300.jpg 195w, https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/wp-content\/uploads\/2020\/05\/Descartes_Princ_philo_92.jpg 654w\" sizes=\"auto, (max-width: 385px) 100vw, 385px\" \/><figcaption id=\"caption-attachment-14910\" class=\"wp-caption-text\"><span style=\"font-size: 10pt\">Sk\u00fdringarmynd \u00far <em>L\u00f6gm\u00e1lum heimspekinnar<\/em> fr\u00e1 1644. Descartes taldi a\u00f0 s\u00e9rhver fastastjarna (t.d. S(\u00f3lin), D, L, F, f og Y ) hef\u00f0i sinn eigin hvirfil og a\u00f0 reikistj\u00f6rnur og halastj\u00f6rnur v\u00e6ru dau\u00f0ar s\u00f3lir. R\u00e6man \u00e1 myndinni \u00e1 a\u00f0 s\u00fdna feril halastj\u00f6rnunnar N, upp og til h\u00e6gri.\u00a0 &#8211;\u00a0 \u00cd disp\u00fatat\u00edunni <em>Um festinguna<\/em> fr\u00e1 1707 segist \u00deorleifur Halld\u00f3rsson vera samm\u00e1la \u00fev\u00ed \u201ea\u00f0 einstakar fastastj\u00f6rnur eigi s\u00e9r vissan sta\u00f0 og st\u00f6\u00f0u fjarri hinum [\u00fe.e.] a\u00f0 stakar fastastj\u00f6rnur eigi s\u00e9r eigin hvirfil.\u201c Hins vegar vill hann ekki fallast \u00e1 \u00fe\u00e1 sko\u00f0un, a\u00f0 \u201ehiminhvelum ver\u00f0i a\u00f0 fj\u00f6lga til samr\u00e6mis vi\u00f0 st\u00e6r\u00f0 e\u00f0a fj\u00f6lda fastastjarna.\u201c \u00deorleifur telur einnig gagnr\u00fdnisvert a\u00f0 halda \u00fev\u00ed fram, a\u00f0 fastastj\u00f6rnuhvirflarnir s\u00e9u k\u00f6nt\u00f3ttir frekar en hring- e\u00f0a hvellaga.<br \/><\/span><\/figcaption><\/figure>\u00cd kenningu Descartes hefur s\u00e9rhver reikistjarna sinn eigin hvirfil, sem er fastur \u00ed hinum risast\u00f3ra s\u00f3larhvirfli. \u00deannig m\u00e1 til d\u00e6mis \u00fatsk\u00fdra, hvers vegna tungl fylgja reikistj\u00f6rnum s\u00ednum og sn\u00faast um \u00fe\u00e6r.<\/p>\n<p><a href=\"https:\/\/en.wikipedia.org\/wiki\/Mechanical_explanations_of_gravitation#Vortex\">\u00deyngdina<\/a> \u00fatsk\u00fdrir Descartes me\u00f0 \u00fev\u00ed, a\u00f0 hvirfilhra\u00f0inn vi\u00f0 yfirbor\u00f0 reikistj\u00f6rnu s\u00e9 mun meiri en sn\u00faningshra\u00f0i hnattarins og <a href=\"https:\/\/plato.stanford.edu\/entries\/descartes-physics\/#ForcCartPhys\">mi\u00f0fl\u00f3ttaafli\u00f0<\/a> s\u00e9 \u00fev\u00ed meira \u00ed hvirflinum en \u00e1 yfirbor\u00f0inu. S\u00e9 hlut sleppt \u00ed vissri h\u00e6\u00f0 er hra\u00f0i hans, og \u00fear af lei\u00f0andi mi\u00f0fl\u00f3ttahneig\u00f0, minni en agnanna \u00ed hvirfilhreyfingunni \u00ed s\u00f6mu h\u00e6\u00f0. Agnirnar \u00fer\u00fdsta honum \u00fev\u00ed ni\u00f0ur \u00fear til hann hann n\u00e6r mi\u00f0fl\u00f3ttajafnv\u00e6gi vi\u00f0 umhverfi sitt, sem gerist \u00e1 yfirbor\u00f0inu.<\/p>\n<p>\u00de\u00f3tt Descartes \u00e6tti s\u00e9r dygga l\u00e6risveina og fylgismenn v\u00ed\u00f0a \u00ed hinum l\u00e6r\u00f0a heimi, f\u00f3r sm\u00e1m saman a\u00f0 draga \u00far vins\u00e6ldum kartes\u00edskrar n\u00e1tt\u00faruspeki \u00e1 fyrri helmingi \u00e1tj\u00e1ndu aldar. \u00dea\u00f0 var a\u00f0 sj\u00e1lfs\u00f6g\u00f0u vegna s\u00edvaxandi \u00e1hrifa Newtons, sem me\u00f0al annars haf\u00f0i <a href=\"https:\/\/www.new-science-theory.com\/isaac-newton-principia-descartes.php\">gagnr\u00fdnt kenningu Descartes<\/a> \u00e1 sannf\u00e6randi h\u00e1tt \u00ed \u00f6\u00f0rum hluta <em>St\u00e6r\u00f0fr\u00e6\u00f0il\u00f6gm\u00e1la n\u00e1tt\u00faruspek-innar<\/em>.<\/p>\n<p>\u00ddmsir fylgismenn hvirlakenningarinnar, einkum \u00ed Frakklandi, reyndu \u00fe\u00f3 a\u00f0 koma \u00ed veg fyrir \u00feessa \u00fer\u00f3un me\u00f0 \u00fev\u00ed a\u00f0 betrumb\u00e6ta kenninguna. Me\u00f0al \u00feeirra, sem t\u00f3ku \u00fe\u00e1tt \u00ed \u00feeirri vonlausu bar\u00e1ttu, voru menn eins og <a href=\"https:\/\/en.wikipedia.org\/wiki\/Christiaan_Huygens\">Huygens<\/a>, <a href=\"https:\/\/en.wikipedia.org\/wiki\/Gottfried_Wilhelm_Leibniz\">Leibniz<\/a>, <a href=\"https:\/\/en.wikipedia.org\/wiki\/Nicolas_Malebranche\">Malebranche<\/a>, <a href=\"https:\/\/mathshistory.st-andrews.ac.uk\/Biographies\/Cassini_Jacques\/\"><span class=\"st\">Jacques Cassini<\/span><\/a> og<a href=\"https:\/\/en.wikipedia.org\/wiki\/Johann_Bernoulli\"> Johann Bernoulli<\/a>.<\/p>\n<ul>\n<li>E. J. Aiton, 1959: <a href=\"https:\/\/www.tandfonline.com\/doi\/pdf\/10.1080\/00033795900200038?needAccess=true\">The Cartesian theory of gravity<\/a>.<\/li>\n<li>E. J. Aiton, 1972: <a href=\"https:\/\/www.amazon.com\/Vortex-Planetary-Motions-History-Science\/dp\/0356038521\">The Vortex Theory of Planetary Motions<\/a>.<\/li>\n<li>E. Slowik, 2017: <a href=\"https:\/\/plato.stanford.edu\/entries\/descartes-physics\/#CartCosmAstr\">Cartesian Cosmology and Astrophysics<\/a>.<\/li>\n<li>F. Ferlin &amp; H. Chabot, 2020: <a href=\"https:\/\/link.springer.com\/referenceworkentry\/10.1007%2F978-3-319-20791-9_156-1\">Vortex Theories in the Early Modern Period<\/a>.<\/li>\n<\/ul>\n<p>\u00cd lokin \u00feetta: Eftirfarandi l\u00fdsingu \u00e1 s\u00f3lkerfinu er a\u00f0 finna \u00ed <em>N\u00e1tt\u00farusko\u00f0ara<\/em> Suhms (bls. 95-98):<\/p>\n<blockquote><p>S\u00f3lin er midt \u00ed vorum S\u00f3lveraldakransi, og hefur allt um kr\u00edng sig \u00feessar 6 pl\u00e1netur edur reikandi stj\u00f6rnur, er svo heita: <em>Merc\u00far\u00edus<\/em>, <em>Venus<\/em>, <em>Mars<\/em>, <em>J\u00f6rdin<\/em> vor med sinni einu fylgistj\u00f6rnu <em>Tunglinu<\/em>, <em>J\u00fap\u00edter <\/em>med s\u00ednum fj\u00f3rum fylgistj\u00f6rnum og <em>Sat\u00farnus<\/em> me\u00f0 s\u00ednum fimm. Sj\u00e1lf stendur <em>h\u00fan <\/em>kyrr \u00ed midju \u00feeirra, a\u00f0 fr\u00e1teknu \u00fev\u00ed, a\u00f0 h\u00fan veltist um kr\u00edng sj\u00e1lfa sig, sem \u00e1 \u00e1si l\u00e9ki, og dregur hinar adrar med ser \u00ed hr\u00edng \u00ed kr\u00edngum sig, hv\u00f6rjar og \u00fear ad auki veltast um \u00e1 leidinni, og s\u00fa hin fyrri hr\u00e6ring \u00feeirra gj\u00f6rir \u00e1rid hj\u00e1 \u00feeim, en s\u00fa s\u00eddari dag og n\u00f3ttu; og \u00e1 sama h\u00e1tt draga \u00fe\u00e6r aptur s\u00ednar fylgistj\u00f6rnur med s\u00e9r \u00ed kringum sig. Rafkrapturinn virdist ad vera n\u00e6rsta h\u00e6filegur ad \u00fatm\u00e1la \u00feetta.<\/p><\/blockquote>\n<p>Danski frumtextinn er fr\u00e1 \u00e1rinu 1763 (\u00feess vegna er \u00daranus ekki me\u00f0 \u00ed upptalningunni) og fyrir utan setninguna um rafkraftinn, m\u00e1 sj\u00e1 greinileg \u00e1hrif fr\u00e1 hvirflakenningunni. \u00deetta \u00e1 einnig vi\u00f0 um byrjunina \u00e1 ne\u00f0anm\u00e1lsgrein J\u00f3ns J\u00f3nssonar (bls. 96-97), sem sty\u00f0st vi\u00f0 b\u00f3k Bastholms, <a href=\"https:\/\/books.google.is\/books?id=A943ngEACAAJ&amp;source=gbs_navlinks_s\">Philosophie for Ul\u00e6rde<\/a>, fr\u00e1 1787 (bls. 18-19). J\u00f3n segir og hefur eftir Bastholm:<\/p>\n<blockquote><p>Hvad \u00fev\u00ed valdi ad s\u00f3lin dregur pl\u00e1neturnar \u00ed kr\u00edng um sig, er ad s\u00f6nnu tors\u00f3tt ad skilja, \u00fe\u00f3 f\u00e6rir Basth\u00f3lm \u00feessa saml\u00edkingu \u00fear til: steinn \u00ed sl\u00f6ngu einni leitast \u00e1 allar siddur ad flj\u00faga \u00fat fr\u00e1 hendi manns, sem er hans midp\u00fanktur. \u00deannig fylgir og pl\u00e1netunum nockurskonar kraptur, ad fl\u00fdja \u00fat fr\u00e1 s\u00ednum midp\u00fankti, sem er s\u00f3lin. En \u00fear er \u00fe\u00e1 annar gagnst\u00e6dur kraptur, sem heldur \u00feeim aptur; og hv\u00f6rr er hann? allir l\u00edkamir hafa einskonar krapt \u00feann \u00ed ser ad draga hv\u00f6rn annann til s\u00edn, t.d. \u00feegar tveir dropar vatns snerta hv\u00f6rr annann, hlaupa \u00feeir saman \u00ed einn dropa. Tveir hnettir \u00ed sama vatni, draga hv\u00f6rr annann til s\u00edn, seu \u00feeir ecki ofl\u00e1ngt hv\u00f6rr fr\u00e1 \u00f6drum. \u00deetta r\u00eds \u00fe\u00f3 af vatninu, sem er \u00ed millum hnattanna, \u00fev\u00ed annadhv\u00f6rt hlj\u00f3ta l\u00edkamirnir ad snerta hv\u00f6rr annann fyrir medal eda medalslaust, skuli \u00feeir hv\u00f6rr annann til s\u00edn draga. \u00c1 \u00feann h\u00e1tt dregur hn\u00f6tturinn \u00fead n\u00e6sta vatn til s\u00edn, \u00feetta vatn aptur \u00fead n\u00e6rsta vatn ser, og s. fr. \u00deannig s\u00fdnist \u00fev\u00ed varid um \u00fe\u00e1 himnesku l\u00edkami. \u00dear er til, sem sagt er <em>[\u00ed 3. ne\u00f0anm\u00e1lsgrein, bls. 11]<\/em> rennandi \u00e6theriskt efni, \u00ed hv\u00f6rju s\u00f3lin og allar hennar pl\u00e1netur sveima. S\u00f3lin dregur \u00feetta efni til s\u00edn, og \u00fead aptur pl\u00e1neturnar. \u00deegar \u00feessi kraptur er jafnst\u00f3r \u00feeim kraptinum, sem dr\u00edfa vill pl\u00e1neturnar \u00fat fr\u00e1 s\u00ednum midp\u00fankti, hlj\u00f3ta \u00fe\u00e6r vafalaust ad flj\u00faga \u00ed kr\u00edngum s\u00f3lina, eins og steinninn \u00ed slaungunni um kr\u00edng h\u00f6ndina.<\/p><\/blockquote>\n<p>\u00dearna er tala\u00f0 um mi\u00f0fl\u00f3ttakraft og einnig um a\u00f0dr\u00e1ttarkraft, sem bendir til einhverrar \u00feekkingar \u00e1 aflfr\u00e6\u00f0i og jafnvel \u00feyngdarfr\u00e6\u00f0i. Einnig voru fornar sem n\u00fdjar vangaveltur um vaka\/straumefni stj\u00f6rnuheimsins vel \u00feekktar me\u00f0al n\u00e1tt\u00faruspekinga \u00e1 uppl\u00fdsingar\u00f6ld. S\u00fa hugmynd, a\u00f0 s\u00f3lin dragi kyrrst\u00e6tt straumefni\u00f0 til s\u00edn og \u00fea\u00f0 aftur reikistj\u00f6rnunnar g\u00e6ti veri\u00f0 t\u00falkun Bastholms \u00e1 vangaveltum <a href=\"https:\/\/en.wikipedia.org\/wiki\/Leonhard_Euler\">L. Eulers<\/a> um samband a\u00f0dr\u00e1ttarkrafts og vaka (sj\u00e1 til d\u00e6mis <a href=\"https:\/\/archive.org\/details\/letterseulertoa00eulegoog\/page\/n321\/mode\/1up\">68. br\u00e9f Eulers til \u00fe\u00fdskrar prinsessu<\/a>). Einna merkilegast vi\u00f0 l\u00fdsinguna \u00ed heild er \u00fe\u00f3, a\u00f0 nafn Newtons kemur \u00fear hvergi vi\u00f0 s\u00f6gu. En hva\u00f0 sem \u00fev\u00ed l\u00ed\u00f0ur, \u00fe\u00e1 er \u00feetta \u00ed fyrsta sinn, sem fjalla\u00f0 er \u00e1 prenta\u00f0ri \u00edslensku um e\u00f0lisfr\u00e6\u00f0ilega ors\u00f6k fyrir sn\u00faningi reikistjarna um s\u00f3lina.<\/p>\n<p>Og \u00fe\u00e1 er loksins komi\u00f0 a\u00f0 \u00fev\u00ed a\u00f0 fjalla um Newton og l\u00f6gm\u00e1l hans. \u00dea\u00f0 ver\u00f0ur gert \u00ed n\u00e6stu f\u00e6rslu.<\/p>\n<p>&nbsp;<\/p>\n<hr \/>\n<p style=\"text-align: center\"><span style=\"font-size: 14pt\">* <a href=\"https:\/\/uni.hi.is\/einar\/2021\/05\/02\/greinaflokkur-um-stjarnedlisfraedi-og-heimsfraedi-a-islandi\/\">Stjarne\u00f0lisfr\u00e6\u00f0i og heimsfr\u00e6\u00f0i \u00e1 \u00cdslandi: Efnisyfirlit<\/a> *<\/span><\/p>\n<hr \/>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Yfirlit um greinaflokkinn Margir sagnfr\u00e6\u00f0ingar vilja rekja upphaf n\u00fat\u00edma stjarne\u00f0lisfr\u00e6\u00f0i til mi\u00f0biks n\u00edtj\u00e1ndu aldar, \u00feegar n\u00fd t\u00e6kni, bygg\u00f0 \u00e1 e\u00f0lisfr\u00e6\u00f0i og efnafr\u00e6\u00f0i, var tekin \u00ed notkun vi\u00f0 ranns\u00f3knir \u00e1 fyrirb\u00e6rum stj\u00f6rnuhiminsins. H\u00e9r er fyrst og fremst \u00e1tt vi\u00f0 hinar mikilv\u00e6gu litr\u00f3fsm\u00e6lingar, en jafnframt lj\u00f3smyndat\u00e6knina, sem var\u00f0 s\u00edfellt gagnlegri eftir \u00fev\u00ed sem t\u00edmar li\u00f0u. Nafni\u00f0 stjarne\u00f0lisfr\u00e6\u00f0i [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,4,9,11,14,15],"tags":[],"class_list":["post-13126","post","type-post","status-publish","format-standard","hentry","category-atjanda-oldin","category-edlisfraedi","category-nitjanda-oldin","category-sautjanda-old","category-staerdfraedi","category-stjornufraedi"],"_links":{"self":[{"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=\/wp\/v2\/posts\/13126","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=13126"}],"version-history":[{"count":0,"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=\/wp\/v2\/posts\/13126\/revisions"}],"wp:attachment":[{"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=13126"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=13126"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wizardly-antonelli.176-10-35-210.plesk.page\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=13126"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}