File:Lunistices in 2006.png

Lunistices_in_2006.png (605 × 340 像素,檔案大小:28 KB,MIME 類型:image/png


摘要

描述
English: Absolute value of declination for lunistices in 2006, a year of a major lunistice. At the bottom are shown the times of phases and ecliipses.

The declination of the lunistices follows a 18.6-year cycle, but with a small 173-day perturbation. The graph shows that in the short term, this perturbation causes much greater changes in declination than the slow change due to moving around the 18.6-year cycle. These perturbations peak when the sun is lined up with the moon's nodes, which is also near the times when eclipses occur. So there are always eclipses, lunar and solar, near the time of the major lunistices, when the moon reaches its furthest north or south point of the 18.6-year cycle, as well as near minor lunistices, when the declinations are closest to zero. These major and minor lunistices occur when the moon's node is near an equinox direction (right ascension 0° or 180°). This means that when the sun lines up with the nodes it is also near an equinox direction, and therefore the major and minor lunistices occur near the moments of the vernal or autumnal equinoxes. If the moment of the sun lining up with the nodes is more than two or three weeks away from an equinox, then the major or minor lunistice will occur around a later or earlier equinox.

Within two weeks before or after the moment of the sun lining up with the nodes there will be both a lunar and a solar eclipse (two weeks apart). About one week after the solar eclipse, in the spring, or three weeks before it, the moon will arrive at right ascension 90° and one of these will be the northern lunistice. In the autumn, this will be about one week before or three weeks after the solar eclipse. In any case, this will happen within about half a month of the sun lining up with the nodes, which as said will be within a couple of weeks of the equinox. The same goes for the southern lunistice.

In 2006, the moment when the node crossed zero right ascension was in June, but the furthest north lunistices were in early April and in mid-September, near the equinoxes, as seen in the graph. Likewise, the furthest south lunistices were in late March and late September.

The dates, inclination, and node were calculated using the mean longitude, mean anomaly, mean elongation, mean node, mean argument of latitude, and mean solar anomaly and the periodic terms for the node and inclination given in "Numerical expressions for precession formulae and mean elements for the Moon and the planets" by the group at the Bureau des Longitudes, Paris, 1994. From the node and inclination, and the obliquity of the earth (assumed constant), one can calculate the location of the lunistice.
日期
來源 自己的作品
作者 Eric Kvaalen

授權條款

我,本作品的著作權持有者,決定用以下授權條款發佈本作品:
w:zh:創用CC
姓名標示 相同方式分享
您可以自由:
  • 分享 – 複製、發佈和傳播本作品
  • 重新修改 – 創作演繹作品
惟需遵照下列條件:
  • 姓名標示 – 您必須指名出正確的製作者,和提供授權條款的連結,以及表示是否有對內容上做出變更。您可以用任何合理的方式來行動,但不得以任何方式表明授權條款是對您許可或是由您所使用。
  • 相同方式分享 – 如果您利用本素材進行再混合、轉換或創作,您必須基於如同原先的相同或兼容的條款,來分布您的貢獻成品。

說明

添加單行說明來描述出檔案所代表的內容
Absolute value of declination for lunistices in 2006. At the bottom are shown the times of phases and ecliipses.

在此檔案描寫的項目

描繪內容

沒有維基數據項目的某些值

檔案來源 Chinese (Taiwan) (已轉換拼寫)

檔案歷史

點選日期/時間以檢視該時間的檔案版本。

日期/時間縮⁠圖尺寸使用者備⁠註
目前2024年3月9日 (六) 19:37於 2024年3月9日 (六) 19:37 版本的縮圖605 × 340(28 KB)Eric KvaalenAdded more periodic terms.
2024年3月3日 (日) 09:47於 2024年3月3日 (日) 09:47 版本的縮圖605 × 340(27 KB)Eric KvaalenUploaded own work with UploadWizard

下列頁面有用到此檔案:

全域檔案使用狀況

以下其他 wiki 使用了這個檔案: