Perceptions of Eclipses in Hindu Mythology
Once the gods and the demons formed an alliance to produce nectar that could give them immortality. As the churned nectar from this ocean was being served to the gods, a demon, disguised as a god, sat between the Sun and the Moon in an attempt to procure the nectar. He was soon recognized by the Sun and the Moon. Seeing him, Lord Visnu immediately severed his head from his body. But, by then the demon had already tasted a small quantity of the nectar and had become immortal and ever since wreak vengeance. The slit head of the demon is known as Rahu and his tail known as Ketu.
Rahu and Ketu are known as two invisible planets in Hindu astrology that at certain times of the year swallow the Sun or the Moon causing either a solar or a lunar eclipse.
Scientifically, the story is a powerful metaphor for what actually happens when an eclipse takes place. Rahu and Ketu are the astronomical points, north and south lunar nodes in the sky.
When the moon overtakes the sun at the place where their paths intersect, it causes the sun or the moon to be hidden from the earth`s view and is thus called a solar or lunar eclipse. The ancient Hindu observers of the sky were aware of the cause of the solar and lunar eclipses and so described the process in the language of metaphor.