Lunar standstill

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Lunar standstill refers to the phenomenon in which the Moon's declination, or the angle between the Moon and the celestial equator, reaches its maximum or minimum value. This event occurs due to the tilt of the Moon's orbital plane relative to the ecliptic plane, which is the apparent path of the Sun across the sky.

Types of Lunar Standstill

There are two types of lunar standstills: major lunar standstill and minor lunar standstill.

Major Lunar Standstill

A major lunar standstill occurs approximately every 18.6 years when the Moon's declination reaches its maximum value of about ±28.6 degrees. During this period, the Moon's path in the sky is at its most extreme, resulting in the highest and lowest moonrises and moonsets.

Minor Lunar Standstill

A minor lunar standstill occurs halfway between major standstills, approximately every 9.3 years. During a minor standstill, the Moon's declination reaches a maximum of about ±18.3 degrees, resulting in less extreme moonrises and moonsets compared to a major standstill.

Astronomical Significance

Lunar standstills are significant in astronomy and astrology as they affect the tidal forces on Earth and can influence cultural and religious practices. The phenomenon is also important for archaeoastronomy, the study of how ancient civilizations understood and utilized astronomical events.

Historical Observations

Ancient cultures, such as the Neolithic people, are believed to have observed and recorded lunar standstills. Sites like Stonehenge and Newgrange are thought to be aligned with the positions of the Moon during these standstills, indicating their importance in ancient astronomical observations.

Modern Observations

Today, lunar standstills are observed using advanced telescopes and astronomical instruments. They continue to be of interest to both professional and amateur astronomers.

See Also

• Lunar cycle
• Precession
• Nutation
• Ecliptic
• Celestial mechanics