Nakshatra

Ardra means the goddess of fortune. The presiding deity the Rudra, the wielder of the trident. Symbol- a teardrop. The ruling planet is Rahu. When Surya enters Ardra the earth is said to be starting its menstrual course that is Ambobachi. Ardra means wet or surcharged with water, that is fat. From Rudra comes all suffering, persecutions and oppressions, anger, ferocity of countenance or hideousness of noise.
Rudra is another name of Shiva. In knowledge, asceticism, renunciation, as also in enjoyment, he is the supreme consummation of all desires. He is the wielder of the most tremendous powers, what could not be attempted far less achieved by other gods. (During the churning of the ocean of milk, poison was produced -which threatened to engulf the universe. Siva came to the rescue and swallowed the poison, holding it in his throat.) On one side he is the symbol of the most perfect placidity and serenity, on the other hand he is the symbol of all that is terrible. He holds the great serpent on his head and on his forehead crescent Chandra with his sweet-soft light. He is at the same time the most peaceful and also the most terrible. And in all these are to be traced the intrinsic characteristics of Ardra.
Those born in the Ardra star are sharp, stable minded, strong, earning by sacrifice, afflicted by sickness, fear and anger. In Tamil and Malayalam Ardra is referred to as Thiruvathirai and Thiruvathira respectively.