In traditional ashtanga yoga practice is refrained from on New Moon and full moon days. It is said that such days are inauspicious for this type of spiritual practice due to the energetic interaction of the Sun & Moon. While it is unlikely to cause harm to the practitioner to do ashtanga on such days many find it more suitable to refrain from practice on such days.
The determination of the moon days is slightly complicated since by this system day is conscidered to start at sunrise unlike the definition of day starting after midnight used when diaries and suchlike list the moon days.
Hence this page has been provided to allow you to easily find the moon days for your current locale.