It has always been the tradition in Ashtanga Yoga to rest from asana practice on new and full moon days (tithis). When asked why we shouldn’t practice on these days, Guruji was fond of saying, “Two ‘planets’ [grahas] one place, very dangerous.” What is meant by this is that on these days, the Sun and the Moon are in a line relative to the position of the Earth. Consequently, their gravitational forces are all combined, and thus the effect of the ‘planets’ more pronounced.

Like all things of a watery nature (human beings are about 70% water), we are affected by the phases of the moon. 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.

When āsana practice is done daily, rest days are important for regeneration; and the extra biweekly ‘moon day’ comes as a welcomed holiday.

Moon days 2017.

January : Thu 12th, Fri 27th
February: Sat 11th, Sat 25th
March: Sun 12th, Mon 27th
April: Tue 11th, Tue 25th
May: Wed 10th, Thu 25th
June: Fri 9th, Fri 23th
July: Sat 8th, Sun 23rd
August: Mon 7th, Tue 22nd
September: Tue 5th, Wed 20th
October Thu 5th, Fri 20th
November: Fri 3rd, Sat 18th
December: Sun 3rd, Mon 18th