Major Lunar Standstill
Major Lunar Standstill occurs every 18.6 years when the moon reaches a maximum monthly range of moonrise/set to the north and south. This range is beyond the range that the sun reaches at solstices. During Major Standstills the lunar nodes are oriented in line with the equinoxes and the high point in the lunar orbit is aligned with the direction of Northern Solstice and the low point with the direction of Southern Solstice to produce an additive effect to achieve maximum declinations to the north and south of the ecliptic. During Major Lunar Standstill eclipses occur near Equinoxes. Since the cycle takes 18.6 years to complete, there are limited opportunities to make direct observations and to document maximum lunar positions at the myriad sites that have possible connections that still exist to any extent. For many ancient sites with putative precision alignments, actual observation, while intriguing, is of limited use because the extreme positions of the sun or moon at the time the alignments were created are no longer attained due to the decreasing obliquity of Earth's orbit over the last few thousand years. However, for general alignments to ancient maximum rising/setting events, positions can be calculated easily from observations near modern maximums.
The next Major Lunar Standstill is in 2025, but the 18.6 year cycle of the moon moves it through a range of maximum declination values that are often measured geocentrically (from the center of the Earth) but for practical observation purposes the moon might not be in the sky at the absolute maximum value for any observer, and even if it is in the sky at that moment, viewer latitude changes the angle at which the moon is seen (parallax) and so that particular date might not be the most extreme position viewable for a particular location. There are other orbital mechanics at play as well. What it really comes down to for observing from a particular location is that the moon already reaches very close to maximum rising/setting positions on the horizon at the end of 2023 and for all of 2024 and 2025 and even into some of 2026. For all of that time it will reach extreme positions every month at various phases and with slight fluctuations (see chart below). The absolute extreme positions are attained near half moons around March and September. The absolute maximum geocentric declination will be March 2025, but again latitude can affect how this looks observationally. Also with that range of years it sounds like a lot of opportunities for viewing, but with some phases hard to observe in daylight and with any cloud interference, the possibilities are reduced. For observation/viewing purposes it ideal to take advantage of every opportunity over these years when conditions are right.
The next Major Lunar Standstill is in 2025, but the 18.6 year cycle of the moon moves it through a range of maximum declination values that are often measured geocentrically (from the center of the Earth) but for practical observation purposes the moon might not be in the sky at the absolute maximum value for any observer, and even if it is in the sky at that moment, viewer latitude changes the angle at which the moon is seen (parallax) and so that particular date might not be the most extreme position viewable for a particular location. There are other orbital mechanics at play as well. What it really comes down to for observing from a particular location is that the moon already reaches very close to maximum rising/setting positions on the horizon at the end of 2023 and for all of 2024 and 2025 and even into some of 2026. For all of that time it will reach extreme positions every month at various phases and with slight fluctuations (see chart below). The absolute extreme positions are attained near half moons around March and September. The absolute maximum geocentric declination will be March 2025, but again latitude can affect how this looks observationally. Also with that range of years it sounds like a lot of opportunities for viewing, but with some phases hard to observe in daylight and with any cloud interference, the possibilities are reduced. For observation/viewing purposes it ideal to take advantage of every opportunity over these years when conditions are right.
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Possible Major Sites for Initial Documentation:
Thornborough Henges Tirghoil standing stone Gaoutabry Dolmen Chûn Quoit Drift Stones La Pierre Droite (Peyrolles) Beaghmore Ballynoe LINK TO MAPS OF MORE SITES |
Click Here for Maximum/Minimum Standstill Dates
calculated for the years of the current Major Standstill.
The link is to a spreadsheet that is view only on the web. The spreadsheet includes more detail than the chart below including declination values, UTC times, and some general notes on rising/setting visibility. If you have a Google account you can click 'File' then 'Make a Copy' so that you can make edits to a specific event date along with an entered site latitude/longitude value and UTC offset amount. This will create links to a table of rise/set times, a horizon diagram with rise/set angles, and a map view with rise/set azimuths. There are also links to discussion where you can ask questions and get more information. More links may be added over time.
calculated for the years of the current Major Standstill.
The link is to a spreadsheet that is view only on the web. The spreadsheet includes more detail than the chart below including declination values, UTC times, and some general notes on rising/setting visibility. If you have a Google account you can click 'File' then 'Make a Copy' so that you can make edits to a specific event date along with an entered site latitude/longitude value and UTC offset amount. This will create links to a table of rise/set times, a horizon diagram with rise/set angles, and a map view with rise/set azimuths. There are also links to discussion where you can ask questions and get more information. More links may be added over time.
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Click on the map pins to see if the event is for rise or set and choose observation dates
with a lunar phase that is most conducive to viewing when rising or setting (see above).
Links above maps go to full screen versions.
with a lunar phase that is most conducive to viewing when rising or setting (see above).
Links above maps go to full screen versions.
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