Purva Ashadha is the twentieth nakshatra, from 253 degrees 20 minutes to 266 degrees 40 minutes of the sidereal zodiac in Sagittarius. Its Vimshottari ruler is Venus, its presiding deities are the Apas, the divine Waters, and its symbol is a fan or a winnowing basket. The name means the earlier invincible or unsubdued one. Jyotisha reads Purva Ashadha through the swelling, unstoppable power of water and the confidence of the undefeated, the rising flood, the fan that spreads influence, and classes it as Manushya gana. Together with Uttara Ashadha it forms the region the tradition links to invincibility and early or lasting victory. These are interpretive conventions laid over the Sagittarius stars that Indian astronomy assigns to this segment.
Purva Ashadha's padas run through Sagittarius, Capricorn, Aquarius and Pisces. The Apas, the Waters personified, are invoked in the Rigveda as purifying and life-giving, addressed directly in hymns asking for healing and blessing, a comparatively impersonal presiding deity compared to the individually named gods of most other mansions, which some commentators connect to the mansion's own reading as raw, elemental, undirected force rather than force channelled through a particular personality. The name Ashadha also designates a specific lunar month in the Hindu calendar, one associated with the onset of the monsoon in much of India, and the seasonal, water-swollen imagery of both Purva and Uttara Ashadha likely draws on that same calendrical association with the rains rather than existing independently of it.