{"id":1461,"date":"2021-03-03T18:29:43","date_gmt":"2021-03-03T17:29:43","guid":{"rendered":"https:\/\/new.ashk.cz\/?p=1461"},"modified":"2021-03-10T20:16:08","modified_gmt":"2021-03-10T19:16:08","slug":"1461","status":"publish","type":"post","link":"https:\/\/www.ashk.cz\/?p=1461","title":{"rendered":"Na no\u010dn\u00ed obloze sv\u00edt\u00ed zv\u00ed\u0159etn\u00edkov\u00e9 sv\u011btlo"},"content":{"rendered":"

Pokud m\u00e1te mo\u017enost \u010di jste dokonce nuceni pob\u00fdvat pr\u00e1v\u011b v n\u00e1sleduj\u00edc\u00edch 14 dnech n\u011bkde mimo velk\u00e1 m\u011bsta, nab\u00edz\u00ed se pozorovat jeden velmi zaj\u00edmav\u00fd \u00fakaz na no\u010dn\u00ed obloze \u2013 zv\u00ed\u0159etn\u00edkov\u00e9 sv\u011btlo. Nejl\u00e9pe je vid\u011bt tam, kde je \u010dist\u00fd vzduch a minim\u00e1ln\u00ed um\u011bl\u00e9 osv\u011btlen\u00ed. M\u016f\u017eeme jej spat\u0159it p\u0159ibli\u017en\u011b hodinu po z\u00e1padu Slunce nad z\u00e1padn\u00edm obzorem jako st\u0159\u00edb\u0159it\u00fd ku\u017eel sv\u011btla t\u00e1hnouc\u00ed se od obzoru do v\u00fd\u0161ky a\u017e 60\u00b0, kde jej dopl\u0148uje pom\u011brn\u011b vz\u00e1cn\u00fd pohled na planetu Mars nedaleko hv\u011bzdokupy Plej\u00e1dy v souhv\u011bzd\u00ed B\u00fdka. Na oba \u00fakazy net\u0159eba dalekohled, jen tmav\u00e1 obloha.<\/p>\n

<\/p>\n

\"Nejl\u00e9pe<\/a>
Nejl\u00e9pe je zv\u00ed\u0159etn\u00edkov\u00e9 sv\u011btlo viditeln\u00e9 po z\u00e1padu nebo p\u0159ed v\u00fdchodem Slunce. Na sn\u00edmku na dokonale tmav\u00e9 obloze na celooblohov\u00e9 mozaice z ostrova Rarotonga v Pacifiku. Foto: Petr Hor\u00e1lek.<\/figcaption><\/figure>\n

Tiskov\u00e1 zpr\u00e1va Fyzik\u00e1ln\u00edho \u00fastavu v Opav\u011b z 2. b\u0159ezna 2021.<\/em><\/p>\n

Zv\u00ed\u0159etn\u00edkov\u00e9 nebo zodiak\u00e1ln\u00ed sv\u011btlo<\/strong> je slune\u010dn\u00ed sv\u011btlo rozpt\u00fdlen\u00e9 na \u010d\u00e1stic\u00edch meziplanet\u00e1rn\u00ed hmoty v\u00a0rovin\u011b Slune\u010dn\u00ed soustavy. Tyto \u010d\u00e1stice, s rozm\u011bry \u0159\u00e1dov\u011b 0,001 \u2013 0,1 mm, poch\u00e1zej\u00ed p\u0159edev\u0161\u00edm z ohon\u016f komet \u010di z drcen\u00fdch meteorit\u016f. Proto\u017ee jsou rozprost\u0159eny p\u0159edev\u0161\u00edm v rovin\u011b Slune\u010dn\u00ed soustavy a ekliptiky (rovin\u011b, na kter\u00e9 le\u017e\u00ed zemsk\u00e1 dr\u00e1ha), prom\u00edt\u00e1 se n\u00e1m sv\u011bteln\u00fd ku\u017eel na oblohu do zv\u00ed\u0159etn\u00edkov\u00fdch neboli zodiak\u00e1ln\u00edch souhv\u011bzd\u00ed. Odtud tedy n\u00e1zev. V oblastech pobl\u00ed\u017e rovn\u00edku je zodiak\u00e1ln\u00ed sv\u011btlo pozorovateln\u00e9 po cel\u00fd rok, nebo\u0165 nikdy nesv\u00edr\u00e1 s obzorem tak mal\u00fd \u00fahel, aby se ztratilo n\u00edzko nad obzorem. Z na\u0161ich zem\u011bpisn\u00fdch \u0161\u00ed\u0159ek jej m\u016f\u017eeme nejl\u00e9pe sledovat okolo rovnodennost\u00ed<\/strong>, na ja\u0159e ve\u010der po soumraku nad z\u00e1padn\u00edm obzorem a na podzim naopak na v\u00fdchod\u011b r\u00e1no p\u0159ed rozb\u0159eskem. V t\u011bchto dob\u00e1ch toti\u017e rovina ekliptiky v na\u0161ich zem\u011bpisn\u00fdch \u0161\u00ed\u0159k\u00e1ch sv\u00edr\u00e1 s obzorem nejv\u011bt\u0161\u00ed \u00fahel a sv\u011btlo je tak nejv\u00edce vyklon\u011bn\u00e9.<\/p>\n

Sv\u011btlo fascinovalo lidi u\u017e odnepam\u011bti.<\/strong> Nezvykl\u00fd a neostr\u00fd ku\u017eel sv\u011btla z\u00e1\u0159\u00edc\u00ed zpoza obzoru na jinak hv\u011bzdami poset\u00e9 obloze, viditeln\u00fd po soumraku nad z\u00e1padn\u00edm obzorem \u010di naopak p\u0159ed rozb\u0159eskem na v\u00fdchod\u011b, nem\u011bl dlouh\u00e1 l\u00e9ta jasn\u00e9 v\u011bdeck\u00e9 vysv\u011btlen\u00ed. S n\u00edm pravd\u011bpodobn\u011b p\u0159i\u0161el jako prvn\u00ed a\u017e zn\u00e1m\u00fd italsk\u00fd astronom Giovannni Domenico Cassini<\/em> (1625-1712), kter\u00fd v roce 1683 zm\u00ednil teorii o rozptylu slune\u010dn\u00edho sv\u011btla na \u010d\u00e1stic\u00edch prachu. Jin\u00e9 zdroje Cassiniho o toto prvenstv\u00ed p\u0159ipravuj\u00ed a tvrd\u00ed, \u017ee za vysv\u011btlen\u00edm jevu stoj\u00ed \u0161v\u00fdcarsk\u00fd matematik Nicolas Fatio de Duillier<\/em> (1664-1753) publikuj\u00edc\u00ed sv\u00e9 pr\u00e1ce jen o rok pozd\u011bji, v roce 1684. A\u0165 tak \u010di onak, o pouh\u00e1 t\u0159i stolet\u00ed pozd\u011bji p\u0159i\u0161la \u00e9ra pokro\u010dil\u00e9 fotografie a prvn\u00ed relativn\u011b p\u011bkn\u00e9 sn\u00edmky ku\u017eele zodiak\u00e1ln\u00edho sv\u011btla byly na sv\u011bt\u011b. Bohu\u017eel p\u0159em\u00edra \u0161kodliv\u00e9ho sv\u011bteln\u00e9ho smogu z\u00a0m\u011bst se zasadila i o postupn\u00e9 zneviditeln\u011bn\u00ed jevu z mnoha m\u00edst na cel\u00e9m sv\u011bt\u011b.<\/p>\n

Sv\u011btlo je bohu\u017eel p\u0159ibli\u017en\u011b 70x slab\u0161\u00ed ne\u017e obloha v p\u0159ez\u00e1\u0159en\u00fdch velkom\u011bstech<\/strong>, a proto je nutn\u00e9 se k jeho spat\u0159en\u00ed pozorovac\u00ed m\u00edsto, kde neru\u0161\u00ed ani sv\u011bteln\u00fd smog, ani p\u0159\u00edpadn\u00e1 mlha. Je samoz\u0159ejm\u011b zapot\u0159eb\u00ed jasn\u00e9ho po\u010das\u00ed. V \u010cesk\u00e9 republice se d\u00e1 \u00fakaz sledovat nap\u0159\u00edklad na Vyso\u010din\u011b, \u0160umav\u011b, v\u00a0Novohradks\u00fdch hor\u00e1ch, v Beskydech, Jesen\u00edk\u00e1ch, na Man\u011bt\u00ednsku \u010di v Orlick\u00fdch a Jizersk\u00fdch hor\u00e1ch (kde jsou oblasti vyhl\u00e1\u0161en\u00e9 jako Rezervace tmy<\/a>), na Slovensku pak z\u00a0horsk\u00fdch oblast\u00ed jako nap\u0159\u00edklad N\u00edzk\u00e9 Tatry, Ve\u013ek\u00e1 a Mal\u00e1 Fatra, ale i Mur\u00e1\u0148sk\u00e1 planina nebo (p\u0159edev\u0161\u00edm) z\u00a0Parku tmavej oblohy Poloniny. Pokud se tedy nach\u00e1z\u00edte pobl\u00ed\u017e t\u011bchto oblast\u00ed \u010di prost\u011b obecn\u011b d\u00e1l od velk\u00fdch m\u011bst<\/strong>, m\u016f\u017eete u\u017e v t\u011bchto dnech vyhl\u00ed\u017eet pom\u011brn\u011b v\u00fdrazn\u00fd sv\u011bteln\u00fd ku\u017eel, s\u00e1paj\u00edc\u00ed do v\u00fd\u0161e a\u017e 60\u00b0 nad obzor, a to v dob\u011b, kdy je Slunce ji\u017e d\u00e9le jak hodinu pod obzorem (tedy kolem 19:00 SE\u010c a pozd\u011bji).<\/p>\n

\"Ku\u017eel<\/a>
Ku\u017eel zv\u00ed\u0159etn\u00edkov\u00e9ho sv\u011btla sahaj\u00edc\u00ed a\u017e k oblouku Ml\u00e9\u010dn\u00e9 dr\u00e1hy v b\u0159eznu 2020 (jasn\u00fd objekt je planeta Venu\u0161e. Na obzoru v\u0161ak z\u00e1\u0159\u00ed \u017elut\u00e9 sv\u011bteln\u00e9 zne\u010di\u0161t\u011bn\u00ed. Foto: Petr Hor\u00e1lek.<\/figcaption><\/figure>\n

Za ide\u00e1ln\u00edch podm\u00ednek<\/strong> (kter\u00e9 panuj\u00ed nap\u0159\u00edklad ve vysokohorsk\u00fdch oblastech v Chile) je mo\u017en\u00e9 spat\u0159it nejen ku\u017eel zodiak\u00e1ln\u00edho sv\u011btla (kter\u00fd je v t\u011bchto oblastech dokonce sp\u00ed\u0161e ru\u0161iv\u00fdm elementem), ale je\u0161t\u011b slab\u0161\u00ed tzv. zodiak\u00e1ln\u00ed most<\/em> spojuj\u00edc\u00ed v\u00fdchodn\u00ed a z\u00e1padn\u00ed zodiak\u00e1ln\u00ed ku\u017eely, \u010di jasn\u011bj\u0161\u00ed m\u00edsto v zodiak\u00e1ln\u00edm most\u011b zvan\u00e9 zodiak\u00e1ln\u00ed protisvit<\/em>. Je to m\u00edsto le\u017e\u00edc\u00ed na opa\u010dn\u00e9 stran\u011b ne\u017e Slunce a \u010d\u00e1stice meziplanet\u00e1rn\u00ed hmoty tam rozptyluj\u00ed nejv\u00edce sv\u011btla, nebo\u0165 jsou \u201ev \u00fapl\u0148ku\u201c. Z\u00a0na\u0161ich kon\u010din se tyto jevy daj\u00ed pozorovat jen jedine\u010dn\u011b, a to sp\u00ed\u0161e fotograficky (p\u0159edev\u0161\u00edm ve zm\u00edn\u011bn\u00fdch oblastech tmav\u00e9 oblohy).<\/p>\n

Nejlep\u0161\u00ed obdob\u00ed pro spat\u0159en\u00ed zv\u00ed\u0159etn\u00edkov\u00e9ho sv\u011btla potrv\u00e1 p\u0159ibli\u017en\u011b do 15. b\u0159ezna, potom ji\u017e za\u010dne M\u011bs\u00edc op\u011bt ru\u0161it sv\u00fdm svitem<\/strong> a zodiak\u00e1ln\u00ed sv\u011btlo p\u0159ez\u00e1\u0159\u00ed. V oblasti pom\u011brn\u011b vysoko nad obzorem, nad nejjasn\u011bj\u0161\u00ed \u010d\u00e1sti b\u011blav\u00e9ho ku\u017eele, najdeme tak\u00e9 planetu Mars<\/strong>, kter\u00e1 se nach\u00e1z\u00ed bl\u00edzko o\u010dima viditeln\u00e9 otev\u0159en\u00e9 hv\u011bzdokupy zvan\u00e9 Plej\u00e1dy v souhv\u011bzd\u00ed B\u00fdka. Nejbl\u00ed\u017ee se bude u kupy prom\u00edtat 4. b\u0159ezna. Zv\u00ed\u0159etn\u00edkov\u00e9 sv\u011btlo pak bude mo\u017en\u00e9 pozorovat je\u0161t\u011b v\u00a0dubnu, konkr\u00e9tn\u011b od 1. do 14. dubna, ale jeho sklon v\u016f\u010di obzoru se bude pomalu zmen\u0161ovat a podm\u00ednky k jeho pozorov\u00e1n\u00ed zhor\u0161ovat.<\/p>\n

Zv\u00ed\u0159etn\u00edkov\u00e9 sv\u011btlo m\u016f\u017eete samoz\u0159ejm\u011b i fotografovat.<\/strong> Nejl\u00e9pe je pozorovateln\u00e9 p\u0159ibli\u017en\u011b 1-2 hodiny po z\u00e1padu Slunce (zapadne-li tedy Slunce nap\u0159\u00edklad v\u00a018 hodin, sv\u011btlo je nejl\u00e9pe viditeln\u00e9 mezi 19. a 20. hodinou). Nejprve je tedy t\u0159eba pro m\u00edsto pozorov\u00e1n\u00ed zjistit \u010das z\u00e1padu Slunce \u2013 nap\u0159\u00edklad p\u0159es www.timeanddate.com\/sun<\/a>.\u00a0 Podle toho pak sta\u010d\u00ed napl\u00e1novat \u010das focen\u00ed. D\u016fle\u017eit\u00fd je rovn\u011b\u017e co nejl\u00e9pe odkryt\u00fd z\u00e1padn\u00ed obzor, ide\u00e1ln\u00ed je fotit z\u00a0vyv\u00fd\u0161eniny nebo kopce. Na samotn\u00e9 focen\u00ed je nutn\u00fd stativ a velkoform\u00e1tov\u00fd apar\u00e1t (zrcadlovka, bezzrcadlovka; rozhodn\u011b neposta\u010d\u00ed mobil) a sv\u011bteln\u00fd \u0161iroko\u00fahl\u00fd objektiv okolo 15 a\u017e 20 mm. Samotn\u00e9 sn\u00edm\u00e1n\u00ed je jednoduch\u00e9 \u2013 po setm\u011bn\u00ed zam\u00ed\u0159it sm\u011brem k\u00a0z\u00e1padn\u00edmu obzoru a zabrat v\u00edce jak 2\/3 oblohy. Na kr\u00e1tk\u00e9 expozice okolo 15-20 sekund p\u0159i vy\u0161\u0161\u00edm ISO a otev\u0159en\u00e9 clon\u011b postupn\u011b fotit no\u010dn\u00ed nebe zaost\u0159en\u00e9 na nekone\u010dno. \u010c\u00edm bude v\u011bt\u0161\u00ed tma, t\u00edm kontrastn\u011bji zv\u00ed\u0159etn\u00edkov\u00e9 sv\u011btlo na sn\u00edmku vynikne jako z\u00e1\u0159iv\u00fd neostr\u00fd ku\u017eel na hv\u011bzdn\u00e9m pozad\u00ed. Na obloze na sn\u00edmc\u00edch najdeme i jasn\u00e9 hv\u011bzdy ze souhv\u011bzd\u00ed B\u00fdka, Orionu nebo (p\u0159i \u0161irok\u00e9m poli) i galaxii v\u00a0Andromed\u011b. Zku\u0161en\u011bj\u0161\u00ed fotografov\u00e9 mohou zkusit tzv. pointovanou fotografii nebo panoramatick\u00e9 sn\u00edm\u00e1n\u00ed.<\/p>\n","protected":false},"excerpt":{"rendered":"

Pokud m\u00e1te mo\u017enost \u010di jste dokonce nuceni pob\u00fdvat pr\u00e1v\u011b v n\u00e1sleduj\u00edc\u00edch 14 dnech n\u011bkde mimo velk\u00e1 m\u011bsta, nab\u00edz\u00ed se pozorovat jeden velmi zaj\u00edmav\u00fd \u00fakaz na no\u010dn\u00ed obloze \u2013 zv\u00ed\u0159etn\u00edkov\u00e9 sv\u011btlo. Nejl\u00e9pe je vid\u011bt tam, kde je \u010dist\u00fd vzduch a minim\u00e1ln\u00ed um\u011bl\u00e9 osv\u011btlen\u00ed. M\u016f\u017eeme jej spat\u0159it p\u0159ibli\u017en\u011b hodinu po z\u00e1padu Slunce nad z\u00e1padn\u00edm obzorem jako st\u0159\u00edb\u0159it\u00fd […]<\/p>\n","protected":false},"author":1,"featured_media":1462,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,5],"tags":[],"class_list":["post-1461","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-nezarazene","category-pozorovani"],"_links":{"self":[{"href":"https:\/\/www.ashk.cz\/index.php?rest_route=\/wp\/v2\/posts\/1461","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ashk.cz\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ashk.cz\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ashk.cz\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ashk.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1461"}],"version-history":[{"count":15,"href":"https:\/\/www.ashk.cz\/index.php?rest_route=\/wp\/v2\/posts\/1461\/revisions"}],"predecessor-version":[{"id":3106,"href":"https:\/\/www.ashk.cz\/index.php?rest_route=\/wp\/v2\/posts\/1461\/revisions\/3106"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ashk.cz\/index.php?rest_route=\/wp\/v2\/media\/1462"}],"wp:attachment":[{"href":"https:\/\/www.ashk.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1461"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ashk.cz\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1461"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ashk.cz\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1461"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}