Talk:Maya calendar/Archives/2012/April

Northward Equinox
HTML2011 - nobody except you ever heard of the "Northward equinox". In astronomy the equinoxes are called the vernal and autumnal equinoxes. You are free to invent a new term for these for your own use, but please don't vandalize the Maya calendar article by putting this in it. Senor Cuete (talk) 02:24, 8 April 2012 (UTC)Senor Cuete

Origin of the Tzolkin - Jose Merida
As far as I can determine, Jose S. Merida is not a mathematician, he is a lay preacher. The length of the tropical year is 365.2422 days. The average length of the cycle of the appearance of Venus is 584 days. Four years is +/- 1461 days. How can you multiply 584 times an integer and get something like 1461 days? 584 * 3 = 1752. "Venus wouldn't be visible during the Vernal equinox due to its proximity to the sun every fourth year"? - nonsense. This looks like unreferenced baloney from an unreliable source to me. When did that get added? I want to remove it. Senor Cuete (talk) 01:04, 9 April 2012 (UTC)Senor Cuete
 * I think you are right. The most approximate cycle is eight years not four, but even this is not exact. If a period of non visibility of venus occurs around the vernal equinox in a particular year, eight years later that would occur again, but it would slightly deviate, and around a few decades later Venus would be visible during the vernal equinox.Japf (talk) 11:15, 9 April 2012 (UTC)

You should try using some planetarium software. It's true that Venus will be too close to the sun to be visible from Mesoamerica during the vernal equinox in 2013, 2017, 2021, etc. — Preceding unsigned comment added by 190.148.47.173 (talk) 16:02, 10 April 2012 (UTC)
 * Close to the sun is not the same as invisible. I'll have to look it up but I think that Venus can be observed something like two days before or after conjunction so it could be close to the sun but not invisible on the equinox in the years you cite. According to my planetarium program you are correct that Venus will be close to the sun on the vernal equinox in 2013, 2017 and 2021 but not every four years before or after that. It was't close in 2001 or 2009 and it will be quite far every four years ahead of the years you mention until at least 2051. I also randomly chose 600 and found that Venus was close to the sun on the equinox in 601 but not in 597 or 605 or during the years 602-605. It appears that what you say about the correlation between the position of Venus and the vernal equinox is not true. In any case Wikipedia is about reliable sources and references and doesn't allow original research. Senor Cuete (talk) 18:19, 10 April 2012 (UTC)Senor Cuete


 * Please see [].


 * The Conjunction of Venus with the Sun happened at march 30th 2001 (9 days after the solstice, so Venus was visible). The conjunction it will be exactly in the of the equinox in 2033, and by the end of century will happen in the beginning of march. So has I stated before, every four years (yes, I said eight) the dates of conjunction repeat, but with slightly deviations which do not allow generalisations for a large period of time. So, the idea of José Mérida is wrong, unless he knew exactly when the Maia calendar was made. Japf (talk) 12:57, 11 April 2012 (UTC)