What is "thiruvathira"

Thiruvathira or Thiruvathirai or Arudhra Darisanam ( Tamil: திருவாதிரை, Malayalam: തിരുവാതിര) is a Hindu festival celebrated in the South Indian states of Kerala and Tamil Nadu. Thiruvathirai(Arudhra) in Tamil means "sacred big wave", using which this universe was created by Lord Shiva about 132 trillion years ago. Chidambaram in Tamil Nadu, the Sri Natarajar temple's annual Festival, is celebrated on this date.