The story of Amavasya is associated with Chandra, the moon God in Hindu tradition and Daksha Prajapati. Legend has it that Daskha Prajapati had 27 daughters. They are the Nakshatras or birth stars in Hindu astrology. Among the 27 wives, Chandra loved Rohini the most. This caused jealousy among other wives who complained to Daksha Prajapati.
Angry Daksha Prajapati cursed Chandra that he will shed all his beauty and radiance for neglecting his daughters. This resulted in Amavasya or no moon day.
Chandra, who lost his luster, then went to Shiva and complained that without his radiance living beings on earth will suffer.
Shiva promised to help him but he also said that he will not completely remove the curse. Thus we have the waxing and waning of moon.
Another legend has it that Chandra is also known as Somdev – one who is the storehouse of Soma, the drink of Devas. It is said that when the Soma drink is completely finished Amavasya happens. Chandra again produces Soma and when he is full it is Purnima. The circle continues.