{"id":676,"date":"2014-08-25T20:26:13","date_gmt":"2014-08-25T18:26:13","guid":{"rendered":"http:\/\/freebook.fernglas-astronomie.de\/?page_id=676"},"modified":"2014-08-25T20:26:13","modified_gmt":"2014-08-25T18:26:13","slug":"hercules","status":"publish","type":"page","link":"http:\/\/freebook.fernglas-astronomie.de\/?page_id=676","title":{"rendered":"Hercules"},"content":{"rendered":"

Hercules is an ancient constellation depicting a kneeling man and has been known under several names since Babylonian times. The striking square from the stars \u03b7, \u03b6, \u03b5 and \u03c0, which depicts his body, is also called Keystone.<\/p>\n

\u03b1 Herculi<\/strong><\/em> is the brightest star of Hercules. It bears the name Ras Algethi<\/em><\/strong>, which probably goes back to the Arab Ras Al Jathiyy and means the \u201chead of the kneeling\u201c \u2013 so, Hercules is upside-down in the sky. Ras Algethi is a red supergiant star whose brightness varies within a period of about 90 days between 3.1 to 3.9m<\/sup> \u2013 not too impressive. Its diameter is about 600 solar diameters. Ras Algethi is together with Mira (\u03bf Ceti) and Betelgeuse (\u03b1 Orionis) one of the largest and coolest known stars in the sky. If it stood in the place of our Sun, it would extend far into the asteroid belt. Nevertheless, it has only a few solar masses. The 380 light-years distant star also has a close companion, but this star is only visible in a telescope.<\/p>\n

.<\/p>\n

\"Obwohl<\/a>
Although M\u200913 is the largest globular cluster visible in North America, it remains only a patch of light even in small telescopes.<\/figcaption><\/figure>\n

M 13<\/strong><\/em> is the largest and most impressive globular cluster which is visible from the Northern Hemisphere. With a brightness of 5.9m<\/sup>, it can be seen under very good conditions even with the naked eye. In binoculars, M\u200913 appears as a starless nebula with a diameter of up to 23 minutes of arc, or about half as large as the full Moon. You need at least 20x magnification to resolve the first of its half a million stars. The globular cluster has a diameter of 160 light-years and is about 23,000 light-years away. Its distance from the center of the galaxy is similar to that of our Sun \u2013 about 30,000 light-years.<\/p>\n","protected":false},"excerpt":{"rendered":"

Hercules is an ancient constellation depicting a kneeling man and has been known under several names since Babylonian times. The striking square from the stars \u03b7, \u03b6, \u03b5 and \u03c0, which depicts his body, is also called Keystone. \u03b1 Herculi is the brightest star of Hercules. It bears the name Ras Algethi, which probably goes … Hercules<\/span> weiterlesen →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":670,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-676","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=\/wp\/v2\/pages\/676","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=676"}],"version-history":[{"count":1,"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=\/wp\/v2\/pages\/676\/revisions"}],"predecessor-version":[{"id":677,"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=\/wp\/v2\/pages\/676\/revisions\/677"}],"up":[{"embeddable":true,"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=\/wp\/v2\/pages\/670"}],"wp:attachment":[{"href":"http:\/\/freebook.fernglas-astronomie.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=676"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}