Lunar standstill moonrise over Chimney Rock in southwestern Colorado. Read more about this photo. The area around Chimney Rock was once inhabited by ancient Pueblo peoples, who left behind what’s now considered a major archaeological site.
The moon’s monthly northerly and southerly extremes in our sky are sometimes called lunar standstills. The moon will reach its southernmost point in our sky for this month tomorrow (March 23, 2014) at 7:28 Universal Time. As measured from the center of the Earth, this will be the first time in the 21st century (2001-2100) that the moon at its southernmost point for the month will swing less than 19o south of the Earth’s equator. And nearly two weeks later – on April 5 – the moon at its northernmost point will swing less than 19o north of the Earth’s equator for the first time this century.
Converting Universal Time to the clock readings in the mainland United States, tomorrow’s lunar standstill – when moon will sweep to its southern extreme on the sky’s dome – will happen at 3:28 a.m. EDT, 2:28 a.m. CDT, 1:28 a.m. MDT or 12:28 a.m. PDT.
Lunar standstills had special significance for the Bronze Age societies who built the megalithic monuments in Britain and Ireland, and for some neo-pagan religions. Evidence also exists that alignments to the moonrise or moonset on the days of lunar standstills can be found in ancient sites of other ancient cultures, such as at Chimney Rock in Colorado and Hopewell Sites in Ohio.
The April 5 and March 23 northern and southern milestones of the moon announce the coming of what’s called a minor lunar standstill year in 2015. That is, next year, the moon’s monthly travels will carry the moon less than 19o north and south of the equator all year long.
Now think back to 2006, which was a major lunar standstill year. In 2006, the moon swung well over 28o north and south of the equator every month. Some 9 years later, during the minor lunar standstill year of 2015, the moon will swing somewhat more than 18o north and south of the Earth’s equator every month.
In 2006, the moon’s maximum southern standstill happened on March 22 (28.725o south), and the maximum northern standstill on September 15 (28.725o north). In 2015, the moon’s minimal southern standstill will occur on September 21 (18.134o south), and the minimal northern standstill on October 3 (18.140o north).
Monthly lunar standstills: 2001 to 2100
In a major or minor lunar standstill year, the maximum (or minimum) northern and southern standstills always happen within a week of a solar eclipse or/and a lunar eclipse, at or near quarter moon and no more than two weeks from an equinox.
Bottom line: The moon will reach its southernmost point in our sky for this month tomorrow (March 23, 2014) at 7:28 Universal Time. It’ll be the first time in the 21st century that the moon at its southernmost point for the month will swing less than 19o south of the Earth’s equator. The moon’s monthly northerly and southerly extremes are sometimes called lunar standstills.
- Earth Sky
