{"id":2104,"date":"2008-09-22T23:45:32","date_gmt":"2008-09-23T07:45:32","guid":{"rendered":"http:\/\/www.ogre.nu\/wp\/?p=2104"},"modified":"2020-10-02T09:27:19","modified_gmt":"2020-10-02T17:27:19","slug":"martian-months","status":"publish","type":"post","link":"https:\/\/bendwavy.org\/wp\/?p=2104","title":{"rendered":"Martian months"},"content":{"rendered":"<p>Most proposed calendars for Mars have 24 months, and various systems have been offered to name them.  Here&#8217;s one more: use the names of the 24 brightest stars, in order of <s>longitude<\/s> right ascension (relative to the rotation axis of Mars), so that each star is conspicuous at night in the month named for it. <!--more--> <\/p>\n<ul>\n<li> Vega (&alpha; Lyrae), Altair (&alpha; Aquilae), Fomalhaut (&alpha; Piscis Austrini), Deneb (&alpha; Cygni), Achernar (&alpha; Eridani), Aldebaran (&alpha; Tauri), Rigel (&beta; Orionis), Capella (&alpha; Aurigae), Betelgeuse (&alpha; Orionis), Canopus (&alpha; Carinae), Sirius (&alpha; Canis Majoris), Adhara (&epsilon; Canis Majoris), Castor (&alpha; Geminorum), Pollux (&beta; Geminorum), Procyon (&alpha; Canis Minoris), Regulus (&alpha; Leonis), Arcturus (&alpha; Bo&ouml;tis), Spica (&alpha; Virginis), Mimosa (&beta; Crucis), Acrux (&alpha; Crucis), Hadar (&beta; Centauri), Rigil Kentaurus (&alpha; Centauri), Antares (&alpha; Scorpii), Shaula (&lambda; Scorpii) <\/li>\n<\/ul>\n<p>But some of these stars are at high <s>latitudes<\/s> declinations; a star near the pole does not move much and so makes an inferior signpost, as well as being out of view to large regions.  So I weighted brightness according to the cosine of declination, and got this list: <\/p>\n<ul>\n<li> Vega, Altair, Alnair (&alpha; Gruis), Fomalhaut, Achernar, Aldebaran, Rigel, Bellatrix (&gamma; Orionis), Capella, Elnath (&beta; Tauri), Betelgeuse, Canopus, Sirius, Castor, Pollux, Procyon, Regulus, Arcturus, Spica, Acrux, Hadar, Rigil Kentaurus, Antares, Shaula <\/li>\n<\/ul>\n<p>Unfortunately for this purpose, bright stars are not evenly distributed: the gap between Achernar and Aldebaran is almost six Martian months, while that between Arcturus and Spica is one day.  So, starting with <a href=\"http:\/\/www.atlasoftheuniverse.com\/stars.html\">a list of 300 bright stars<\/a>, I looked for the smallest RA gap and removed the dimmer star (as weighted), repeating until 24 remained: <\/p>\n<ul>\n<li> Vega, Altair, Alnair, Fomalhaut, Achernar, Markab (&alpha; Pegasi), Diphda (&beta; Ceti), Alpheratz (&alpha; Andromedae), Hamal (&alpha; Arietis), Mirfak (&alpha; Persei), Capella, Sirius, Procyon, Dubhe (&alpha; Ursae Majoris), Regulus, Alioth (&epsilon; Ursae Majoris), Alkaid (&eta; Ursae Majoris), Porrima (&gamma; Virginis), Arcturus, Muhlifain (&gamma; Centauri), Acrux, Rigil Kentaurus, Antares, Shaula <\/li>\n<\/ul>\n<p> The widest gap is 46.6 days, the narrowest 15.4 (a bit over half a month).<\/p>\n<p>I thought of this years ago, but only now got around to writing the code to generate the list. (I have no obvious way of checking its accuracy.)<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Most proposed calendars for Mars have 24 months, and various systems have been offered to name them. Here&#8217;s one more: use the names of the 24 brightest stars, in order of longitude right ascension (relative to the rotation axis of &hellip; <a href=\"https:\/\/bendwavy.org\/wp\/?p=2104\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[73],"tags":[57],"class_list":["post-2104","post","type-post","status-publish","format-standard","hentry","category-calendars","tag-calendar"],"_links":{"self":[{"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/2104","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2104"}],"version-history":[{"count":23,"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/2104\/revisions"}],"predecessor-version":[{"id":2116,"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=\/wp\/v2\/posts\/2104\/revisions\/2116"}],"wp:attachment":[{"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2104"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2104"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bendwavy.org\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2104"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}