Eclipses are universally regarded as exceedingly inauspicious and ritually perilous events.
Indian astronomers, like those of many other cultures, were able to work out the motion of the moon and, as a result, were able to forecast both solar and lunar eclipses pretty correctly.
The narrative of the Tortoise avatar, in which gods and demons join forces to churn the Ocean of Milk into the nectar of immortality, which they would subsequently share, is the traditional mythological explanation for eclipses.
The gods deceive the demons out of their part, but when the gods divide it up, the demon Sainhikeya disguises himself and enters their midst.
The sun and moon warn the deity Vishnu of Sainhikeya's presence as he starts to drink, and Vishnu promptly cuts off the demon's head with his discus.
However, after drinking part of the nectar, the demon's head and trunk have both become eternal, with the head becoming Rahu and the trunk becoming Ketu.
Rahu has a special dislike for the sun and moon, the gods who brought him death, and wants to devour them anytime he sees them in the sky.
He always succeeds, but they escape unhurt through Rahu's severed neck since he no longer has a body to digest them.
Eclipses are considered inauspicious and ritually dangerous because to their relationship with Rahu, and in popular culture, eclipses are said to radiate malevolent rays with a physical character.
As a result of this hazard, many people choose to stay inside for the duration of an eclipse.
People typically practice rituals of protection during eclipses, including providing contributions (dana) to stave off possible bad luck.
Pregnant women must be especially cautious, should the bad luck of the day influence the developing child.
Some people think that pregnant women should lay motionless during eclipses because they are afraid that the infant would be delivered without the body part that the lady moved.
People wash (snana) and undertake other purification ceremonies after the eclipse to eradicate any remaining impurities (ashaucha) or ill luck.
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