Shiva became Chandrashekhara
Parvati once asked Shiva, Lord, tell me, why do you wear a crescent moon on your forehead? What is the story behind this?
Shiva told her the story.
Earlier, Parvati had been born as Sati, the daughter of Daksha. As Sati, she had been married to Shiva. Since Daksha insulted her husband Shiva, Sati gave up her life.
When Sati died, Shiva no longer found pleasure in anything. He began to live in the forest and started to perform tapasya. Such was the power of the tapasya that any trees or mountains that were near the place where Shiva was meditating used to be burnt into ashes. As Shiva moved from place to place, the earth started to burn and wither away . The gods were greatly alarmed at these developments. They went to Brahma to seek advice as to how the earth might be saved.
Brahma, said, Let us take the moon god Chandra with us and make a present of him to Shiva. Chandra’s visage is so pleasing that Shiva may feel happy and pacified.
The gods placed Chandra in a pot of amrita (a life-giving drink). They also had another pot that was full of poison. With these two pots they went to Shiva and offered him the pots.
Brahma said, The gods have brought you two pots. Please accept them.
Shiva first accepted the pot that contained the amrita. As soon as he did this, the crescent moon came out and got fixed to Shiva’s forehead. Next Shiva accept the pot of poison and touched it with his middle finger. He touched his throat with the finger and the throat became blue. That is the reason why Shiva is known as Nilakantha, blue of throat (this is another story to prove that Shiva is also known as Nilakantha, the earlier story of which shows that Shiva is called Nilakantha is during the samudra manthanam). And because the moon is like a crown to Shiva. Shiva is called Chandrashekhara.
At the sight of the moon, Shiva was pacified.
OM NAMO NARAYANAYA