At the traditional astronomical basis of Songkran, the sun enters Aries. This solar transition is known as a move into the first sign of the zodiac and historically marked the beginning of a new year in Thailand.
The name Songkran is connected with a Sanskrit term meaning movement or passage, reflecting the sun’s apparent movement from one zodiac position to another. The festival therefore began as a calendar and seasonal transition, not simply as a water celebration.
Modern Songkran customs preserve that New Year symbolism through cleaning, temple visits, merit-making, family reunions, and respectful water rituals. Public water play is a later, highly visible expression of the festival rather than its entire meaning.
Because modern calendars and local customs do not always use identical astronomical calculations, the public holiday dates are conventionally fixed in April. Aries remains the key zodiac sign associated with Songkran’s traditional origin.