Karthika Pournami or Powrnami or Poornima is a Hindu festival, celebrated on the Pournami / Powrnami (full moon) day or the fifteenth lunar day of the Karthika (Nov-Dec) . it is also known as Tripuri Poornima and Tripurari Poornima. It is sometimes called Deva-Dewali or Deva Deepawali – the festival of lights of the Gods. Tripuri Poornima or Tripurari Poornima is derives from the name Tripurari – the foe of the demon Trupurasura. In some legends of Karthika Poornima, the term is used to denote the three demons (Killer of Tripurasura) killed Tripurasura on this day. Tripurasura had conquered the whole world and defeated the gods and also created three cities in space, together called “Tripuras” . the killing of the demon(s) and destruction of his / their cities with a single arrow – by Lord Shiva overjoyed the gods and they declared the day as a festival of illuminations. This day is also called “Deva- Deepawali of the Gods. Deepawali is the Hindu festival of lights.
Karthika Pournami is also the birthday of Matsya, God Vishnu’s fish – incarnation (Avathar). It is also the birth day of Vrinda, the personification of the Tulasi plant and of Karthikeya, the God of war and son of Shiva. This day is also considered special for Radha, the lover of Krishna – Vishnu’s incarnation. It is believed that Krishna and Radha danced rasa and Krishna worshiped Radha on this day.
The festival has even more significance when the day falls in the Nakshathra (lunar mansion) Krithika and is then called Maha Karthika. The Nakshathra is Bharani, the results are stated to be special. If it is Rohini nakshathra, then the fruitful results are even much more. Any philanthropic act on this day is supposed
to bring benefits and blessings equal to the performing of ten yajnas (sacrifices).