What is a Moon Day?
In Ashtanga Yoga practice, a Moon Day is the day on which a full or new moon exerts its strongest influence.
So What?
Regular Ashtanga Yoga practitioners should not practice on Moon days. The day of rest is the day of your regular practice time nearest to the approaching new or full moon.
Tim Miller’s website is often referred to on why this is:
Like all things of a watery nature (human beings are about 70% water), we are affected by the phases of the moon. The phases of the moon are determined by the moon’s relative position to the sun. Full moons occur when they are in opposition and new moons when they are in conjunction. Both sun and moon exert a gravitational pull on the earth. Their relative positions create different energetic experiences that can be compared to the breath cycle. The full moon energy corresponds to the end of inhalation when the force of prana is greatest. This is an expansive, upward moving force that makes us feel energetic and emotional, but not well grounded. The Upanishads state that the main prana lives in the head. During the full moon we tend to be more headstrong.
The new moon energy corresponds to the end of exhalation when the force of apana is greatest. Apana is a contracting, downward moving force that makes us feel calm and grounded, but dense and disinclined towards physical exertion.
The Farmers Almanac recommends planting seeds at the new moon when the rooting force is strongest and transplanting at the full moon when the flowering force is strongest.
Practicing Ashtanga Yoga over time makes us more attuned to natural cycles. Observing moon days is one way to recognise and honour the rhythms of nature so we can live in greater harmony with it.
Why do the Moon Days on this page, not always correspond to the days of full and new moon specified on the calendar, and scientific websites?
Mathew Sweeney:
Although the observance of the Moon day is a good thing, not practicing on the exact day of the full Moon and new Moon is usually a day too late. Rigidly following the Moon day timetable is exactly the opposite of intuitively feeling the Moon energy. In this case you are using your Surya mind rather than connecting with your Moon belly. Feeling when it is appropriate not to practice, feeling when the Moon is drawing to it's lowest, or peaking to it's highest requires a bit more letting go, and a bit more awareness, but well worth it. As the cycle waxes towards the full Moon, it is the process of peaking and expanding that we can feel. As the cycle wanes towards the new Moon, it is the process of reducing and contracting that we can feel. By the time the Moon is actually full, for example, it is too late. From the process point of view, at its very peak the Full Moon energy is already moving towards the "new". One problem with this, will mean different students will not practice on different days depending how they feel. Thus it becomes difficult to keep a structured day off, the logical weekly timetable will be disrupted. Keep in mind, that in terms of energy, the Moon has no rational logic to it.”
Why are the moon days sometimes occurring on different dates in other territories?
The moon is not completely full or new for an arbitrarily nominated day or 24 hour period. The moon is completely full or new, only for a moment. In different time zones the completely full or new moon occurs at different times of day. And therefore sometimes on different days. For instance, in Bangkok in 2010 the moon was full on the 8th of October at 1:44 am. London is 6 hours behind Bangkok, so in London the moon was completely full at 7:44 pm on the 7th of October, the previous day.