#Ardra is the name of a #nakshatra in Hindu astrology, the sixth depending on numbering scheme used. The Sanskrit name Ārdrā translates to “green” or “the moist one”. It is associated with the star Betelgeuse (α Ori). The presiding deity is #Rudra, its symbol is a #teardrop, and the ruling planet is #Rahu. In Tamil and Malayalam, Ardra is referred to as Tiruvātirai and Tiruvātira respectively.

Thiruvathira or Thiruvathirai or Arudhra Darisanam is a Hindu festival celebrated in the Indian states of Tamil Nadu and Kerala. In Thillai Chidambaram 10-day Festival is held during Thiruvathirai. On the 9th day night Maha Abhishekam will be done to Lord Nataraja. It takes place on the full moon night in the Tamil month of Margazhi (December–January) and this is also the longest night in a year. If you observe the moon and its Nakshatras crossing one by one, we understand the significant days of these festival and uncover new layers of meaning. It starts with Rohini‑Hyades on the 8th day, and of Mriga‑shiras‑Labda Orionis on the 9th day and finally during the night after the 9th day we see the full moon in #Arudra-­ #Betelgeuse.

Winter Chariot Festival is Margari Tiruvadirai that happens in the holy Ardra in the month of Margari. Margari being the month of the middle of December till the middle of January. It is same time during Winter Solstice, even Christmas is celebrated, and this is also the longest night in a year.

Most of the temples around the world with Lord Nataraja and Shiva as deity perform the Arudhra Darshan during this day.

Arudra or cosmic dance of Nataraja represents five activities — Creation, Protection, Destruction, Embodiment and Release. It is essentially a Shaivite festival and celebrates the cosmic dance of Lord Shiva, which is represented by the Nataraja form. Arudhra (Thiruvathirai in Tamil) signifies the golden red flame and Shiva performs the dance in the form this red-flamed light. Lord Shiva is supposed to be incarnated in the form of Lord Nataraja during the Arudra Darshan day.

Thiruvathira is the nakshatra or “ #star” of Lord Shiva as per the Malayalam calendar. It is believed that on this day, the Goddess Parvathi finally met Lord Shiva after her long penance and Lord Shiva took her as a saha-dharma chaarini (equal partner). Both Parvathi and Shiva present this ideal to devotees in the form of #Ardhanarishvara (half male, half female form).

The Skanda Purana also mentions that Brahmā once had an argument with Rudra, during which Rudra decapitated one of Brahma’s heads (originally, he had five). Rudra threw the head into space, and it became the stars of Mṛgaśīrṣā, the nakshatra which comes after Brahma’s Rohini. Searching (mṛga) for the head (śira), Rudra came to reside in the nakshatra next to Mṛgaśīrṣā, Ārdrā.
https://www.farfaraway.co/blog/ardra-nakshatra-characteristics